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Ti-based alloys 2024

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Please wait a minute... For Selected: Download Citations EndNote Ris BibTeX Toggle Thumbnails Select Martensite decomposition under thermal-mechanical coupling conditions to fabricate an ultrafine-grained Ti6Al4Mo4Zr1W0.2Si alloy Taoyu Zhou, Jiuxu Yang, Nan Li, Hao Sun, Bohua Zhang, Zibo Zhao, Qingjiang Wang J. Mater. Sci. Technol.    2023, 168: 157-168.   DOI: 10.1016/j.jmst.2023.05.052 Abstract （35）      PDF       Knowledge map    The fabrication of ultrafine-grained microstructures (grain size below 1 μm) in titanium alloys is beneficial for improving their mechanical properties at room temperature and medium temperatures (400-550 °C). However, a long-standing challenge involves the low-cost manufacturing of bulk ultrafine-grained titanium alloys. In this work, we developed a facile strategy through martensite decomposition at thermal-mechanical coupling conditions, to fabricate an equiaxed microstructure in a Ti6Al4Mo4Zr1W0.2Si model alloy with an average α grain size of 315 ± 62 nm. The formation of the ultrafine-grained microstructure was because the lattice strain stored in the martensitic initial microstructure enhanced the nucleation rate of dynamic recrystallization, meanwhile, the pinning role of martensite decomposition products β and (Ti, Zr)5Si3 phases suppressed grain coarsening at high temperatures. Compared to conventional (α+β) alloys, the tensile strength of this alloy improved by 20%-30% at both room temperature and 550 °C, without decreasing its ductility. In situ SEM observations revealed that the ultrafine-grained microstructure would not only suppress dislocation motions but also contribute to the homogenous deformation in the matrix of the material, therefore, it resulted in higher mechanical performance. The research results may be of great significance to the development of next-generation aviation titanium alloys. Reference | Related Articles | Metrics Select Enhanced antibacterial activity, corrosion resistance and endothelialization potential of Ti-5Cu alloy by oxygen and nitrogen plasma-based surface modification Xiaotong Zhao, Jiali Hu, Jingjun Nie, Dafu Chen, Gaowu Qin, Erlin Zhang J. Mater. Sci. Technol.    2023, 168: 250-264.   DOI: 10.1016/j.jmst.2023.04.076 Abstract （40）      PDF       Knowledge map    Antibacterial Ti-5Cu alloy is a promising substitute material for Ti-made cardiovascular implants, so its surface engineering is crucial to expediting clinical implementation. Given the antibacterial and cardiovascular biological benefits of Cu2+ and titanium-nitride-oxide (TiNxOy) coatings, a Cu2O/CuO-TiNxOy coating with upregulated Cu2+ release was successfully deposited on Ti-5Cu alloy for the first time using oxygen and nitrogen plasma-based surface modification. The superhydrophilic and nanostructured Cu2O/CuO-TiNxOy coating had a dense structure and was well bonded to the substrate, resulting in enhanced corrosion resistance, while CuO/Cu2O in the coating released Cu2+ faster than Ti2Cu phase in the matrix. More gratifying, the coating demonstrated perfect antibacterial properties (R > 99.9% against S. aureus), owing primarily to direct contact sterilization of Cu2O/CuO. The most encouraging phenomenon was that the coating dramatically accelerated HUVEC adhesion (1.4 times), proliferation (RGR: 106%-116%), and particularly migration (RMR: 158%-247%) compared with the control Ti. The coating extract also significantly stimulated in vitro angiogenesis capacity. The rapid endothelialization for Cu2O/CuO-TiNxOy coating was attributed to the surface nanostructure and Cu2+/NO2- release, which upregulated the angiogenesis-related gene expression of HIF-1α, VEGF, and eNOS to increase VEGF secretion and NO production. All of the findings indicated that the Cu2O/CuO-TiNxOy coating could enhance the corrosion resistance, antibacterial properties, and endothelialization potential of Ti-Cu alloy, displaying great clinical potential in cardiovascular applications. Reference | Related Articles | Metrics Select Microstructure evolution and phase transformation of the mushy zone in a quenched β-solidifying TiAl alloy Fuqiang Zhang, Xianfei Ding, Leming Xu, Xin Feng, Hai Nan, Jianping He, Yongfeng Liang, Junpin Lin J. Mater. Sci. Technol.    2024, 169: 28-41.   DOI: 10.1016/j.jmst.2023.05.070 Abstract （59）      PDF       Knowledge map    This study investigates the phase constitutions and transformations that occur in the mushy zone and in the adjacent phase fields of a directionally solidified Ti-44Al-8Nb-1Cr alloy via quenching technique. The results indicate that the mushy zone consists of unmelted β dendrites and interdendritic liquid, whose formation can be attributed to the difference in melting point aroused by local heterogeneity in solutecontent. The β dendrite is composed of numerous subgrains with various orientations. During quenching, the β dendrite transforms into Widmanstätten α via a precipitation reaction, owing to the decreasing cooling rate caused by heat transfer from the surrounding liquid. Additionally, after quenching, the interdendritic liquid is transformed into γ plates. Within the single β phase field and the lower part of the mushy zone, a massive transformation of β to γ occurs . Conversely, in the β+α phase field, both β and α phases are retained to ambient temperature. During the heating process, the transformation of α → β gives rise to the formation of β variants, which affects the orientation of β dendrites in the mushy zone. The growth kinematics of the α → β transformation was elucidated, revealing the preferential growth directions of 〈111〉 and 〈112〉 for β variants. Furthermore, this study presents an illustration of the formation process of the mushy zone and the microstructural evolution during the heating and quenching process. Reference | Related Articles | Metrics Select Improving the high cycle fatigue property of Ti6Al4V ELI alloy by optimizing the surface integrity through electric pulse combined with ultrasonic surface rolling process Pengfei Sun, Shengguan Qu, Chenfeng Duan, Xiongfeng Hu, Xiaoqiang Li J. Mater. Sci. Technol.    2024, 170: 103-121.   DOI: 10.1016/j.jmst.2023.06.029 Abstract （35）      PDF       Knowledge map    To improve the surface integrity and high cycle fatigue property of Ti6Al4V ELI alloy, the electric pulse has been introduced into the ultrasonic surface rolling process (USRP), which is called electric pulse-assisted ultrasonic surface rolling process (EUSRP). With the help of “electroplasticity” of the electric pulse, the thickness of the surface gradient deformation layer was about three times of the USRP specimens by adjusting the pulse current level. However, the surface hardness decreases due to the continuous effect of the pulse current and the “skin effect” during treatment. It is worth noting that the higher the applied pulse current, the more severe the softening. This paradox causes the fatigue performance of EUSRP specimens lower than that of USRP specimens. To break this paradox, the EUSRP treatment is followed by a USRP treatment. The EUSRP-2 (with a pulse current of 200 A) +USRP specimens exhibit excellent surface hardness, a gradient deformation layer thickness of about 400 µm, low surface roughness and high compressive residual compressive stress. Besides, the hardening mechanisms of the different surface strengthening specimens have been quantitatively analyzed in combination with microstructure analysis. The fatigue life of Ti6Al4V ELI alloy can be improved by about 25 times at 780 MPa using the EUSRP-2+USRP treatment, the main reason for the highest fatigue life is the deepest surface gradient layer and the deepest crack initiation site. The fatigue limit of the EUSRP-2+USRP specimens is not the highest because too much surface hardening causes compressive residual stress relaxation during cycling and the beneficial effect of compressive residual stress is eliminated. Reference | Related Articles | Metrics Select Achieving superior performance in powder-metallurgy near-β titanium alloy by combining hot rolling and rapid heat treatment followed by aging Fucheng Qiu, Tuo Cheng, Yuchao Song, Orest M. Ivasishin, Dmytro G. Savvakin, Guangyu Ma, Huiyan Xu J. Mater. Sci. Technol.    2024, 171: 24-36.   DOI: 10.1016/j.jmst.2023.06.034 Abstract （57）      PDF       Knowledge map    Heat treatment plays an important role in tailoring the mechanical properties of powder-metallurgy (PM) titanium alloys. However, only limited work about the rapid heat treatment (RHT) of PM titanium alloys has been reported. In this work, RHT was applied to PM Ti-5Al-5Mo-5V-1Cr-1Fe alloy after hot rolling to study the evolution of its mechanical properties and the influence of residual pores on its properties. Through hot rolling and annealing, a fine and uniform α + β structure with few residual pores is obtained. During RHT, the primary α dissolves gradually and completes in the β region, and the β grains then grow, resulting in the continuous decrease in elongation after aging. Moreover, the tensile strength first increases and then decreases with increasing RHT temperature, owing to the increase in volume fraction of secondary α in α + β region and the β grain growth in β region. In contrast to the RHT of cast-and-wrought titanium, the negative influence of residual pores lowers the RHT temperature for obtaining the highest tensile strength to a temperature below the β-transus temperature. Despite the negative influence of the residual pores, retained primary α and fine β grains with fine secondary α inside contribute to achieving a good strength/ductility balance (1570 MPa and 6.1%, respectively). Additionally, although at higher cycles to failure, the negative influence of residual pores increases as it affects the crack initiation zone at the subsurface, the good resistance of secondary α to fatigue crack propagation still enhances the fatigue strength considerably (about 300 MPa). This work suggests a cost-effective strategy to produce titanium alloys with high performance. Reference | Related Articles | Metrics Select Bridging microstructure and crystallography with the crack propagation behavior in Ti-6Al-4V alloy fabricated via dual laser beam bilateral synchronous welding Tingyan Yan, Yuan Liu, Jianfeng Wang, Yong Zheng, Xiaohong Zhan J. Mater. Sci. Technol.    2024, 174: 1-14.   DOI: 10.1016/j.jmst.2023.05.058 Abstract （66）      PDF       Knowledge map    The microstructure evolution and crack propagation behavior were systematically and thoroughly investigated in α/β Ti-6Al-4V alloy obtained under the inhomogeneous heating effect of a coupled dual laser beam via a combination of postmortem electron backscattering diffraction analyses and numerical simulations. The effect of microstructural attributes (grain size, grain boundary, dislocation) on the fracture property and crack propagation behavior was investigated based on thermodynamic and crystallographic analyses, as well as the examinations of dislocation density and the Burgers vector. By quantifying the degree of variant selection using the degree of variant selection (DVS) equation, it was found that the higher the energy input, the weaker the variant selection, as the secondary α phase suppresses further dislocation-induced variant selection via autocatalytic nucleation and growth. The proportion of high angle grain boundaries (HAGBs) concentrated around 60° gradually increases with improving cooling rate, mainly due to the change in the tendency of martensite transformation to be induced. The grain refinement was the primary mechanism for the enhancement of Ti-6Al-4V alloy T-joints, while the suppression of crack propagation by HAGBs also played a crucial role in improving strength and ductility. The crack propagation direction frequently changes when the order is approximately parallel to the short axis of α′ martensite grains, forming a zigzag propagation path. The above findings should shed light on optimizing dual laser beam bilateral synchronous welding (DLBSW) technology to tailor the microstructure and improve the mechanical properties of Ti-6Al-4V alloy T-joints. Reference | Related Articles | Metrics Select Uncovering the hierarchical clusters in the heat-affected zone of an electron beam welded α/β titanium alloy joint C. Xu, X.H. Shao, H.J. Yang, M. Lv, H.Q. Liu, X.L. Ma J. Mater. Sci. Technol.    2024, 174: 120-132.   DOI: 10.1016/j.jmst.2023.07.038 Abstract （58）      PDF       Knowledge map    Using high-resolution transmission Kikuchi diffraction (TKD) and transmission electron microscopy (TEM), we examined the hierarchical clusters that form in situ in the heat-affected zone (HAZ), which are commonly referred to as “ghost” structures, of bimodal titanium alloy Ti-5Al-2Sn-2Zr-4Mo-4Cr (wt%, TC17). The ghost structures are enriched with Al elements but poor in Mo and Cr compared to the surrounding β matrix. TKD results show that the ghost structure in middle-HAZ mainly consists of αL laths with a high-angle grain boundary, which exhibits the classic Burgers orientation relationship (BOR) with the host matrix, while it encircles the αP grains in far-HAZ. And the ghost structure is evidenced to form via incomplete martensitic transformation. TEM results further confirm that the ghost structure is composed of αL and tiny βL laths with BOR, with the former being enriched with Al and poor with Cr and Mo, while the latter is the opposite. Interestingly, two αL variant clusters with a check-mark morphology are frequently observed viewed along [0001]αL//[110]βL directions, which are dominated by the crystallographic and geometrical relationships between α and β phases. Based on the microstructural characterization, it is hypothesized that the ghost structure is transformed from the initial αP phase, due to the coupling effect of high thermal stress (which induces the formation of a large number of dislocations) and element diffusion caused by sudden temperature increase and plunge cooling in the HAZ during the welding process. Reference | Related Articles | Metrics Select Simultaneous enhancements of strength and toughness by multiscale lamellar structure in Ti2AlNb based intermetallic Fan Zhang, Weidong Zeng, Penghui Zhang, Haoyuan Ma, Jianwei Xu J. Mater. Sci. Technol.    2024, 174: 249-261.   DOI: 10.1016/j.jmst.2023.07.056 Abstract （52）      PDF       Knowledge map    Multi-scale lamellar structure significantly improves toughness of Ti2AlNb based alloys, which are inherently brittle intermetallics, without compromising their strength. This structure was achieved through-B2-transus-forging (TBTF) combined with O + B2 two-phase region heat treatments. Various types of multi-scale lamellar structures were obtained by controlling the cooling rate after TBTF. These variations were mainly attributed to differences in the distribution, content, and size of the thick lamellar O phase and the size and crystallographic orientation of B2 grain. By analyzing the microstructural characteristics and crystallographic orientation near the crack propagation path, it was found that the crack propagation resistance of thick lamellae, sub grain and grain boundaries (GBs) O phase increased sequentially, accompanied by more tortuous crack propagation path. Moreover, B2 grains with high misorientation significantly deflected the crack propagation by cleavage ridges between adjoining cleavage planes. Additionally, the development of numerous secondary cleavage ridges, resulting from the transition through varying secondary cleavage planes in distinct sub B2 grains, further hindered the quick propagation of cracks. It was clarified that the cleavage planes were dominantly belonging to {110}. These findings provided valuable guidance for the design of damage tolerance strategies for Ti2AlNb-based intermetallics. Reference | Related Articles | Metrics Select Simultaneous enhancement of strength and ductility in high Nb-TiAl by Si alloying Jun Cao, Tielong Sun, Zhichao Guo, Hui Xue, Yongfeng Liang, Junpin Lin J. Mater. Sci. Technol.    2024, 177: 128-132.   DOI: 10.1016/j.jmst.2023.09.008 Abstract （44）      PDF       Knowledge map    High-Nb-containing TiAl (High Nb-TiAl) alloys are considered as a new generation of TiAl alloys for applications at higher temperatures. However, their poor room-temperature (RT) mechanical properties, such as near-zero plasticity, significantly limit their applications. To promote the practical applications of high Nb-TiAl alloys, this study investigated the utilization of Si alloying to improve the mechanical properties of these alloys by in situ precipitation of micro-/nanosilicides during the casting process. In particular, S segregation and equiaxed γ grains can improve the plasticity of the alloy, whereas micro-/nanosilicides can strengthen the alloy via the second-phase strengthening effect. The combined effects of S segregation and the ability to generate high-density silicides result in simultaneous enhancement of ultimate tensile strength and plasticity of the alloy at RT and 850 °C. Reference | Related Articles | Metrics Select Influence of welded pores on fatigue behavior of TC17 titanium alloy welded joints subjected to gigacycle regime at room and high temperatures Fulin Liu, Yao Chen, Lang Li, Chong Wang, Qingyuan Wang, Yongjie Liu J. Mater. Sci. Technol.    2024, 178: 1-21.   DOI: 10.1016/j.jmst.2023.09.006 Abstract （69）      PDF       Knowledge map    Welded structures in aero-engines commonly operate in high-temperature environments, making them susceptible to reduced fatigue life and premature failure due to welding defects within the structure. Thus, the gigacycle fatigue behaviors of titanium alloy welded joints at both room temperature (RT) and 400 °C were investigated, aiming to uncover the mechanism behind the formation of fine granular area (FGA) surrounding welded pores. The research findings demonstrate that the S-N curves of TC17 titanium alloy electron beam welded joint undergo a transition from a single linear decline at RT to a bilinear decline at 400 °C. However, the fatigue failure mode remains unaffected by temperatures, and crack initiation is attributed to welded pores. By utilizing the Chapetti model curve to modify the Kitagawa-Takahashi (K-T) diagram, the lower threshold stress amplitude is introduced, enabling the determination of a safe size for welded pores at 400 °C, which is calculated to be 11.3 µm. Additionally, the Gumbel probability distribution function is employed to assess the maximum size of welded pores. Finally, based on dislocation interactions, the formation mechanism of the FGA consisting of discontinuous nanograins with high-density dislocations is elucidated. Reference | Related Articles | Metrics Select Creep rupture life prediction of high-temperature titanium alloy using cross-material transfer learning Changlu Zhou, Ruihao Yuan, Baolong Su, Jiangkun Fan, Bin Tang, Pingxiang Zhang, Jinshan Li J. Mater. Sci. Technol.    2024, 178: 39-47.   DOI: 10.1016/j.jmst.2023.08.046 Abstract （72）      PDF       Knowledge map    High-temperature titanium alloys are the key materials for the components in aerospace and their service life depends largely on creep deformation-induced failure. However, the prediction of creep rupture life remains a challenge due to the lack of available data with well-characterized target property. Here, we proposed two cross-materials transfer learning (TL) strategies to improve the prediction of creep rupture life of high-temperature titanium alloys. Both strategies effectively utilized the knowledge or information encoded in the large dataset (753 samples) of Fe-base, Ni-base, and Co-base superalloys to enhance the surrogate model for small dataset (88 samples) of high-temperature titanium alloys. The first strategy transferred the parameters of the convolutional neural network while the second strategy fused the two datasets. The performances of the TL models were demonstrated on different test datasets with varying sizes outside the training dataset. Our TL models improved the predictions greatly compared to the models obtained by straightly applying five commonly employed algorithms on high-temperature titanium alloys. This work may stimulate the use of TL-based models to accurately predict the service properties of structural materials where the available data is small and sparse. Reference | Related Articles | Metrics Select Insights into the role of W/B alloying on high-temperature oxidation behavior of Ti42Al5Mn alloy Pengxiang Zhao, Hui Ma, Xiaobing Li, Ming Gao, Yingche Ma, Kui Liu J. Mater. Sci. Technol.    2024, 178: 188-200.   DOI: 10.1016/j.jmst.2023.09.011 Abstract （32）      PDF       Knowledge map    In this study, the oxidation behavior of Ti42Al5Mn, Ti42Al5Mn0.5 W, Ti42Al5Mn0.5W0.1B, and Ti42Al5Mn0.8 W was investigated at 800 °C. Due to the inability to form a dense protective Al2O3 layer, Ti42Al5Mn suffered severe spallation during oxidation at 800 °C and the mass gain was significant. The intermediate layer between the scale and the substrate was first composed of Laves/Z phase but changed to α2/Z phase with prolonged oxidation. The intermediate layer with high Ti/Al ratio favors the formation of a thick Al2O3 + TiO2 mixed layer in the oxide scale which is prone to initiate cracks and cause the spalling of oxides. The doping of W in TiO2 effectively inhibited its generation and promoted the formation of a dense Al2O3 layer, resulting in a significant improvement in the oxidation resistance of the alloy. Compared to Ti42Al5Mn alloy, Ti42Al5Mn0.8 W showed no spallation after 300 h cyclic oxidation and the kinetic curve changed from liner law to parabolic law. The intermediate layer of Ti42Al5Mn0.8 W alloy was composed of a single Laves phase and remained unchanged even after 1000 h oxidation at 800 ℃, offering a favorable basis for the generation of a stable protective oxide layer in the alloy. The addition of 0.1 at.% B to Ti42Al5Mn0.5 W alloy refined its microstructure and further improved its spallation resistance to a level close to that of Ti42Al5Mn0.8 W alloy. Reference | Related Articles | Metrics Select Relationship between β→α dynamic transformation and dynamic recrystallization under thermomechanical coupling in Ti-5Al-5Mo-5V-1Cr-1Fe alloy Yue Dong, Xingang Liu, Hao Xu, Yini He, Yujiao Ke, Wenwen Zhang J. Mater. Sci. Technol.    2024, 179: 98-113.   DOI: 10.1016/j.jmst.2023.05.061 Abstract （37）      PDF       Knowledge map    The thermal simulation compression tests of near-β titanium alloy Ti-5Al-5Mo-5V-1Cr-1Fe were performed within the range of deformation temperatures of 710-860 °C and strain rates of0.001-1 s-1. Based on electron backscatter diffraction (EBSD) characterization and analysis technology, the interaction between dynamic phase transformation (DPT) of β-to-α and dynamic recrystallization (DRX) under thermal-mechanical coupling is deeply and systematically explored. We clarify the effects of temperatures and strain rates on the orientation relationship during dynamic precipitation of α-phase within β grain interiors possessing special orientation. The results show that the intragranular α-phase precipitated on the subgrain boundaries near {001}β with a high degree of dynamic recovery (DRV) deviates more from Burgers Orientation Relationship (BOR) than the α-phase that precipitates near {111}β as temperature increases. The proportion of α-phase precipitated by strain-induced on β recrystallized equiaxed grains for the deviating angle from BOR (θBOR) in the range of 20°-30° increases to 40% with the increase of strain rates below 800 °C. In addition, the α-phase is dynamically precipitated on the grain boundaries with {110}β orientation, which undergoes continuous dynamic recrystallization (CDRX), exhibiting epitaxial recrystallization, namely {110}β//{0001}α. Furthermore, the morphology of grain boundaries α phase (αGBs) precipitated by strain-induced phase transformation (SIPT) on specific types of β grain boundaries (βGBs), as well as the crystallographic orientation relationship and variant selection effect between adjacent α-variant within β grains are elucidated. The orientation relationships between α variants in {111}β grain are related with each other by 50°-60°/<-12-10> and 60°-70°/<-48-43> rotation. The “necklace” αGBs of recrystallization exhibit mainly the rotation of 50°-70° around the 〈2-310〉 zone axis, while the adjacent α-variant in the grain interiors is mainly 60° or 90°/<12-30>. In summary, the study has contributed to a deeper understanding of the deformation behavior and DPT laws of β-to-αp in near-β titanium alloy, which lays a foundation for the optimization of the hot deformation process and mechanical properties. Reference | Related Articles | Metrics Select In-situ study of damage mechanisms in Mg-6Li dual-phase alloy Jing Li, Li Jin, Sangbong Yi, Xin Zhang, Jie Dong, Ming Luo J. Mater. Sci. Technol.    2024, 179: 114-124.   DOI: 10.1016/j.jmst.2023.09.018 Abstract （31）      PDF       Knowledge map    Interfaces play a crucial role in influencing the mechanical properties of Mg alloys. For Mg-Li dual-phase alloy, the type of interfaces is complex, which includes both grain boundary and phase boundary, and the influence of such interfaces on the damage nucleation is yet to be explored. In this paper, in-situ scanning electron microscopy (SEM) based measurements were carried out to investigate the meso-scale damage nucleation mechanisms of the Mg-6Li dual-phase alloy. Results show that 94.8% of cracks are nucleated at the α-Mg grain boundary in the post-uniform elongation stage, while 5.2% are at phase boundary and almost no crack at the β-Li grain boundary. The initiation of α-Mg grain boundary cracks is attributed to strain incompatibility, which induces micro-strain localization, and then causes grain boundary sliding (GBS) and crack nucleation. Deformation compatibility analysis reveals that the geometric compatibility factor (Mk) can be used to predict the nucleation of α-Mg grain boundary crack. When Mk is lower than0.075, α-Mg grain boundary cracks tend to form. Few cracks are generated at the phase boundary is due to the mild strain partitioning between α-Mg phase and β-Li phase and may also be partly attributed to multiple slip systems in body-centered cubic (BCC)-structured β-Li phase, which can accommodate well with the deformation of adjacent α-Mg phase. Reference | Related Articles | Metrics Select Medical titanium surface-modified coatings with antibacterial and anti-adhesive properties for the prevention of implant-associated infections Dongliang Huo, Fengqian Wang, Fengjuan Yang, Tongyao Lin, Qing Zhong, Sui-Ping Deng, Jingxian Zhang, Shaozao Tan, Langhuan Huang J. Mater. Sci. Technol.    2024, 179: 208-223.   DOI: 10.1016/j.jmst.2023.09.016 Abstract （60）      PDF       Knowledge map    Implant-associated infections (IAIs) caused by drug-resistant bacteria remain a critical factor in the failure of implant procedures. Therefore, it is urgent to develop an effective anti-infection coating for implant surface modification to prevent IAIs. Herein, an antibacterial and anti-adhesive coating (CMP-Ti) constructed on the surface of titanium implants is reported, formed by the nanomaterial CeO2@Mn3O4 NRs (CM NRs) with antibacterial activity and the superhydrophilic polymer polyethylene glycol (PEG). The nanocatalyst CM NRs on the surface of CMP-Ti induce ferroptosis-like death of bacteria by catalyzing the production of hydroxyl radical (?OH) and singlet oxygen (1O2) and the consumption of glutathione (GSH). The superhydrophilic coating of CMP-Ti can effectively prevent adherence of drug-resistant bacteria and avoid biofilm formation. By combining the “active offense” antibacterial mechanism with the “passive defense” anti-adhesion mechanism, CMP-Ti can kill bacteria and inhibit biofilm formation. The results of in vivo studies showed that CMP-Ti effectively prevented implant-associated infections caused by Methicillin-resistant Staphylococcus aureus (MRSA), thus promoting tissue repair and osseointegration. Therefore, this multifunctional coating combining “active offense” and “passive defense” provides a promising way to prevent IAIs caused by drug-resistant bacteria and to promote tissue repair in the future. Reference | Related Articles | Metrics Select Simultaneously enhancing the hot workability and room-temperature strength of Ti-6Al-4V alloy via adding Mo and Fe Jie Shen, Zhihao Zhang, Jianxin Xie J. Mater. Sci. Technol.    2024, 180: 32-44.   DOI: 10.1016/j.jmst.2023.04.054 Abstract （40）      PDF       Knowledge map    Reducing the hot working temperature and high-temperature deformation resistance of titanium alloy to improve hot rolling and hot extrusion workability of products with thin walls and complex section shapes has always been an important topic in the field of titanium alloy processing. This paper proposed a strategy of adding Mo and Fe elements to simultaneously reduce the hot working temperature and high-temperature deformation resistance of Ti-6Al-4V alloy. The effects of Mo and Fe contents on the microstructure, β transus temperature (Tβ), and high-temperature flow stress (HFS) of Ti-6Al-4V-xMo-xFe (x=0-5) alloys were investigated. The results showed that adding Mo and Fe can substantially reduce the Tβ and HFS of the alloy, and greatly improve its room-temperature strength. Compared with commercial Ti-6Al-4V samples, the Tβ of Ti-6Al-4V-2Mo-2Fe and Ti-6Al-4V-3Mo-3Fe samples was decreased by 68-98 °C, and the HFS at 800-900 °C was decreased by 37.8%-46.0%. Compared with hot-rolled Ti-6Al-4V samples, the room-temperature tensile strength of hot-rolled Ti-6Al-4V-2Mo-2Fe samples was increased by about 30%, while the elongation hardly decreased. The increased strength was mainly attributed to fine grain strengthening and solid solution strengthening. The hot workability and room-temperature strength of Ti-6Al-4V alloy can be significantly improved by adding 2-3 wt.% Mo and Fe simultaneously. Reference | Related Articles | Metrics Select High temperature self-lubricating Ti-Mo-Ag composites with exceptional high mechanical strength and wear resistance Yu Zhen, Minghui Chen, Chengtao Yu, Zongbang Yang, Yang Qi, Fuhui Wang J. Mater. Sci. Technol.    2024, 180: 80-90.   DOI: 10.1016/j.jmst.2023.09.012 Abstract （41）      PDF       Knowledge map    Titanium alloys are of keen interest as lightweight structural materials for aerospace and automotive industries. However, a longstanding problem for these materials is their poor tribological performances. Herein, we designed and fabricated a multiphase Ti-Mo-Ag composite (TMA) with heterogeneous triple-phase precipitation (TPP) structure by spark plasma sintering. A lamellar α-phase (αL) precipitates from the β-phase under furnace cooling conditions and maintains a Burgers orientation relationship (BOR) with β-matrix. An active eutectic transition also occurs in the titanium matrix, resulting in TiAg phase. The intersecting acicular TiAg and lamellar αL cut β grains into fine blocks and the primary equiaxed α phase also provides many interfaces with β phase, which together effectively impede dislocation movement and increase strength. Compared with other titanium composites, TMA with TPP microstructure gets an excellent combination of strength (yield strength 1205 MPa) and toughness (fracture strain 27%). Furthermore, the TPP structure endows TMA with strong cracking resistance, which aids in reducing abrasive debris at high temperatures during sliding and obtaining a low wear rate. Simultaneously, Ag particles distributed at grain boundaries will easily diffuse to the wear surface, in situ forming the necessary lubricating phase Ag2MoO4 with Mo-rich matrix debris via oxidation. TMA possesses excellent tribological properties with especially low wear rate of 8.0 × 10-6 mm3N-1m-1 and friction coefficient (CoF) of merely 0.20 at 600 °C. Unlike other self-lubricating composites with high volume fraction of soft ceramic lubricants, which inevitably sacrifice their mechanical strength and ductility, the composite TMA possesses well-balanced strength, toughness and self-lubricating properties. It holds important implications to design other metal matrix self-lubricating composites (MMSCs) used for load-bearing moving parts. Reference | Related Articles | Metrics Select Enhanced low cycle fatigue properties of selective laser melting Ti-6Al-4V with fine-tuned composition and optimized microstructure Yuqi He, Fengying Zhang, Yuhong Dai, Kexin Zhao, Zimeng Ye, Zerong Yu, Chao Xia, Hua Tan J. Mater. Sci. Technol.    2024, 180: 129-140.   DOI: 10.1016/j.jmst.2023.09.017 Abstract （46）      PDF       Knowledge map    Improving the low-cycle fatigue (LCF) properties of additively manufactured Ti-5.6Al-3.8V alloy is critical in ensuring its service safety and represents a significant research challenge. This work discusses a solution that optimizes the alloy's microstructure and ductility by precisely controlling the over-saturated strengthening elements and heat treatment. This was accomplished using selective laser melting (SLM), heat treatment at 800 °C for 2 h, and furnace cooling on a Ti-5.6Al-3.8V alloy with tightly controlled Al, V, and O concentrations in a lower range. The results showed that the SLM-fabricated Ti-5.6Al-3.8V alloy, post-heat treatment, exhibited α laths with a width of ～1.4 μm and β columnar grains with a diameter of ～126 μm, without experiencing coarsening or variant selection phenomena. The alloy balanced strength and ductility post-heat treatment with a UTS of 1015 MPa and an EL of 16.5% relative to the as-deposited state (UTS of 1199 MPa and EL of 11.9%). Notably, the LCF properties of the heat-treated SLM Ti-5.6Al-3.8V alloy are superior to those of other Ti-6Al-4V alloys produced by additive manufacturing and comparable to traditional forgings. At high strain amplitudes (1-1.5%), the fatigue life of this alloy was twice that of the Ti-6Al-4V forgings. Furthermore, we comprehensively analyzed the microstructure, strength, and ductility of the SLM Ti-5.6Al-3.8V alloy to elucidate the factors influencing its LCF properties. These findings provide a solid foundation for improving the LCF properties of additively manufactured Ti-6Al-4V alloy, thereby contributing to its safe and reliable use in critical applications. Reference | Related Articles | Metrics Select The rapid densification behavior of powder metallurgy Ti alloys by induction heating sintering Kejia Pan, Xiaotao Liu, Bao Wang, Shuai Gao, Shixing Wu, Ning Li J. Mater. Sci. Technol.    2024, 181: 152-164.   DOI: 10.1016/j.jmst.2023.10.009 Abstract （48）      PDF       Knowledge map    Micropores are decisive to mechanical properties and thermal deformation capabilities of powder metallurgy (P/M) Ti alloys sintered compacts. As a result, achieving express densification is of prime importance and has attracted increasing attention recently. Induction heating owns the merits of high efficiency, short process, and low cost, and thus has huge potential to be used as a sintering approach for the fabrication of P/M Ti alloys. Nevertheless, the facilitated densification behavior associated with induction heating sintering remains unclear so far. To address it, powder metallurgy Ti6Al4V is manufactured via induction heating sintering with which the underlying sintering mechanism is investigated in-depth. It is found that induction heating could generate a fully densified compact in a remarkably shortened time, demonstrating its superior sintering efficiency as compared with conventional resistance furnace heating. COMSOL finite element analysis reveals that the maximum current density during induction heating can reach 106 A m-2 though the magnetic field strength is solely 0.02 T, leading to a slight temperature difference of approximately 30 °C between the interior and exterior of the billet. Furthermore, the rapid heating essentially starts at sharp corners of particles due to the potent current concentration effect, which facilitates the cracking of the particle surface oxide film and thus enhances the direct contact between them. Moreover, the electromigration effect caused by induction current promotes the diffusion capability of elements, giving rise to expedited densification, alloying, and chemical homogenization. This work provides not only critical insight into the sintering mechanism of induction heating sintering but also significant guidance for low-cost powder metallurgy materials preparation. Reference | Related Articles | Metrics Select Improving thermal stability and creep resistance by Sc addition in near-α high-temperature titanium alloy Xiuyang Zhong, Tongsheng Deng, Wenlong Xiao, Xiaochun Liu, Zhi Liu, Yucheng Yang, Olanrewaju A. Ojo J. Mater. Sci. Technol.    2024, 183: 1-11.   DOI: 10.1016/j.jmst.2023.09.056 Abstract （57）      PDF       Knowledge map    High-temperature titanium alloys' thermal stability and creep resistance are significant during service in high temperatures. This study systematically investigated the thermal stability and mechanical properties of Ti-6.5A1-2.5Sn-9Zr-0.5Mo-1Nb-1W-0.3Si-xSc (x, 0-0.5 wt.%) at 650 °C. The lamellar secondary α phase is refined and the formation of Sc2O3 is increased with the increasing scandium (Sc) additions, which improves the strength of the alloy, while excessive Sc2O3 becomes the crack source and deteriorates the plasticity. The oxygen content in the matrix is reduced by the interaction between Sc and oxygen, inhibiting the growth of the Ti3Al phase and improving the thermal stability of the alloy. Meanwhile, Sc accelerates the dissolution of the residual β phase and precipitation of fine, diffusely distributed ellipsoidal silicides, which strongly prevents dislocation movement. The enhancement of creep resistance for the Sc-containing alloy is attributed to the refined lamellar secondary α phases, Sc2O3 particles, Ti3Al phase, and silicides, especially the precipitated silicides. Eventually, the 0.3Sc alloy shows optimal thermal stability (the plasticity loss rate 17.3%) and creep resistance (steady-state creep rate 4.4 × 10-7 s-1). The investigation results provide new insights into the mechanism and thermal stability improvement in high-temperature titanium alloys modified by rare earth (RE). Reference | Related Articles | Metrics Select Advances in additively manufactured titanium alloys by powder bed fusion and directed energy deposition: Microstructure, defects, and mechanical behavior H.Y. Ma, J.C. Wang, P. Qin, Y.J. Liu, L.Y. Chen, L.Q. Wang, L.C. Zhang J. Mater. Sci. Technol.    2024, 183: 32-62.   DOI: 10.1016/j.jmst.2023.11.003 Abstract （33）      PDF       Knowledge map    Ti and its alloys have been broadly adopted across various industries owing to their outstanding properties, such as high strength-to-weight ratio, excellent fatigue performance, exceptional corrosion resistance and so on. Additive manufacturing (AM) is a complement to, rather than a replacement for, traditional manufacturing processes. It enhances flexibility in fabricating complex components and resolves machining challenges, resulting in reduced lead times for custom designs. However, owing to distinctions among various AM technologies, Ti alloys fabricated by different AM methods usually present differences in microstructure and defects, which can significantly influence the mechanical performance of built parts. Therefore, having an in-depth knowledge of the scientific aspects of fabrication and material properties is crucial to achieving high-performance Ti alloys through different AM methods. This article reviews the mechanical properties of Ti alloys fabricated by two mainstream powder-type AM techniques: powder bed fusion (PBF) and directed energy deposition (DED). The review examines several key aspects, encompassing phase formation, grain size and morphology, and defects, and provides an in-depth analysis of their influence on the mechanical behaviors of Ti alloys. This review can aid researchers and engineers in selecting appropriate PBF or DED methods and optimizing their process parameters to fabricate high-performance Ti alloys for a wide range of industrial applications. Reference | Related Articles | Metrics Select Effect of grain boundary Widmanstätten α colony on the anisotropic tensile properties of directed energy deposited Ti-6Al-4V alloy Wei Fan, Yijie Peng, Yongxia Wang, Yang Qi, Zhe Feng, Hua Tan, Fengying Zhang, Xin Lin J. Mater. Sci. Technol.    2024, 184: 145-156.   DOI: 10.1016/j.jmst.2023.09.057 Abstract （47）      PDF       Knowledge map    Columnar grain structure caused anisotropy in mechanical properties, especially in elongation, is an important concern for Ti-6Al-4 V alloy fabricated by directed energy deposition (DED). Several strategies have been proposed to reduce anisotropy by globularizing the grains, but these conventional approaches are costly and inefficient due to challenges faced during producing the columnar β-grain structures. However, understanding the impact of columnar grain-related microstructures on the anisotropic deformation behavior is still necessary. Despite the recognition of the importance of grain boundary Widmannstätten α colony (αWGB) as a grain-related microstructure, it has received limited attention in available literature on anisotropy in mechanical properties. This study employed in-situ induction heating during DED to control αWGB formation, yielding three Ti-6Al-4 V samples with varying αWGB sizes. Anisotropic deformation of αWGB and its impact on elongation in build and transverse directions were analyzed. αWGB width grew from 0.5 µm to 32.4 µm via diffusion-controlled growth due to reduced cooling rate. Transverse deformation led to dislocation movement and accumulation, causing early failure and worsened ductile anisotropy within αWGB. Notably, larger αWGB size significantly exacerbated anisotropy in ductility. This work underscores αWGB's role in anisotropic deformation and offers insights for optimizing mechanical properties in DED-fabricated titanium alloys. Reference | Related Articles | Metrics Select Microstructure dependence of electrochemical corrosion resistance for rapidly solidified Ti50Al48Mo2 alloy Chonghao Sun, Ruilin Xiao, Kelun Liu, Ying Ruan, Bingbo Wei J. Mater. Sci. Technol.    2024, 185: 58-68.   DOI: 10.1016/j.jmst.2023.10.043 Abstract （34）      PDF       Knowledge map    The rapid solidification of undercooled liquid Ti50Al48Mo2 alloy was achieved by the electromagnetic levitation (EML) technique. At small and medium undercoolings, primary (βTi) dendrite reacted with surrounding liquid to drive a peritectic transformation into the (αTi) phase. The solutal Mo and Al segregations were located within the dendrite center and the grain boundary during peritectic transformation, consequently B2 phase in the dendrite center and γ phase at the grain boundary formed. Once undercooling exceeded 253 K, the peritectic transformation was completely inhibited, and the formation of the B2 phase and γ phase was completely suppressed. The ultrafine eutectoid structure was formed and a complete solute trapping effect was realized. Homogeneous solute distribution facilitated the formation of thicker passivation film with lower defect density and higher film resistance on the alloy surface. Moreover, this weakened micro-galvanic effect reduced the susceptibility to pitting corrosion, and consequently the corrosion resistance of the alloy was improved. Reference | Related Articles | Metrics Select Inverse gradient nanostructure through gradient cold rolling demonstrated with superelasticity improvement in Ti-50.3Ni shape memory alloy Jian Zhang, Ke Liu, Tong Chen, Chen Xu, Chen Chen, Dingshun Yan, Ann-Christin Dippel, Jun Sun, Xiangdong Ding J. Mater. Sci. Technol.    2024, 185: 233-244.   DOI: 10.1016/j.jmst.2023.12.003 Abstract （44）      PDF       Knowledge map    Gradient nanostructured (GNS) metallic materials are commonly achieved by gradient severe plastic deformation with a gradient of nano- to micro-sized structural units from the surface/boundaries to the center. Certainly, such GNS can be inversely positioned, which however has not yet been reported. The present work reports a facile method in deformation gradient control to attain inverse gradient nanostructured (iGNS), i.e., tailoring the cross-section shape, successfully demonstrated in Ti-50.3Ni shape memory alloy (SMA) wire through cold rolling. The microstructure of the rolled wire is characterized by a macroscopic inverse gradient from boundaries to the center—the average sizes of grain and martensite domain evolve from micrometer to nanometer scale. The iGNS leads to a gradient martensitic transformation upon stress, which has been proved to be effectively reversible via in-situ bending scanning electron microscopy (SEM) observations. The iGNS Ti-50.3Ni SMA exhibits quasi-linear superelasticity (SE) in a wide temperature range from 173 to 423 K. Compared to uniform cold rolling, the gradient cold rolling with less overall plasticity further improves SE strain (up to 4.8 %) and SE efficiency. In-situ tensiling synchrotron X-ray diffraction (SXRD) analysis reveals the underlying mechanisms of the unique SE in the iGNS SMAs. It provides a new design strategy to realize excellent SE in SMAs and sheds light on the advanced GNS metallic materials. Reference | Related Articles | Metrics Select Quasi-in-situ investigation on complete lamellar fragmentation of β-solidified TiAl alloy during uniaxial isothermal compression Yonghao Yu, Hongchao Kou, Xiaoxuan Xu, Zilong Zhang, Yarong Wang, Mengyu Jia, Yuqing Li, Fengming Qiang, Jinshan Li J. Mater. Sci. Technol.    2024, 186: 132-141.   DOI: 10.1016/j.jmst.2023.11.024 Abstract （33）      PDF       Knowledge map    The coarse as-cast lamellar microstructure in TiAl alloys is difficult to be broken completely by thermomechanical processing. Some remnant lamellar colonies in the deformed microstructure seriously affect the microstructural homogeneity and deteriorate the properties. In this study, it is found that by isothermal compression at 1230 °C and 1250 °C, the lamellar colonies of Ti-43.5Al-4Nb-1Mo-0.1B (TNM) alloys can be completely broken. This is attributed to the weakened anisotropic deformation behavior of the lamellar colonies due to the isothermal holding treatment before deformation. The deformation behavior at 1230 °C was investigated by quasi-in-situ experiments. It is observed that the regions near lamellar colony boundaries first undergo dynamic recrystallization at small strain, while the lamellar colonies gradually break down with increasing strain. The adequate fragmentation of lamellar colonies mainly depends on the recrystallization of α lamellae (αL). The isothermal holding at 1230 °C leads to an increase in the content and thickness of αL, which allows it to assume more deformation and promotes its recrystallization by reaching critical strain. The interrupted γ lamellae (γL) formed by decomposition during isothermal holding facilitates the occurrence of α recrystallization within the lamellar colonies by hindering dislocation movement. In addition, recrystallized γ grains (γR) are gradually dissolved by the formation of α precipitates inside them through the γ → α phase transformation and the subsequent consumption of α precipitates by the recrystallized α grains. Reference | Related Articles | Metrics Select Insights into the microstructural design of high-performance Ti alloys for laser powder bed fusion by tailoring columnar prior-β grains and α-Ti morphology S.X. Wang, S.F. Li, X.M. Gan, R.D.K. Misra, R. Zheng, K. Kondoh, Y.F. Yang J. Mater. Sci. Technol.    2024, 187: 156-168.   DOI: 10.1016/j.jmst.2023.11.055 Abstract （51）      PDF       Knowledge map    A high-performance Ti-Ni-B alloy with good tensile properties and reduced mechanical anisotropy was developed by promoting the columnar to equiaxed transition (CET) of prior-β grains and modifying α-laths to equiaxed grains. Both Ni and B contributed to the refinement of columnar prior-β grains during the L→β phase transformation by generating constitutional undercooling. Compared with Ni, B had a superior capability of generating constitutional undercooling, which not only replaced a significant amount of Ni with a minor addition to reduce the formation of brittle eutectoid, but also reacted with Ti to form TiB to promote heterogeneous nucleation of α-Ti grains during the β→α phase transformation. Together with the restricted growth of α-laths induced by the refinement of prior-β grains, a fully equiaxed α-Ti structure was obtained. The competition between the negative effect of brittle eutectoid and the positive role of α-lath to equiaxed grain transition on the ductility of as-printed Ti-Ni-B alloys was fundamentally governed by the morphology of eutectoid and technically dependent on the Ni-B content. When the addition was 1.2Ni-0.06B (wt.%) or less, the positive effect of α-lath on equiaxed grain transition can effectively mitigate the issue of reduced ductility caused by brittle eutectoid. In contrast, at 1.8Ni-0.09B or greater, the negative effect of eutectoid dominated. New insights into microstructural design obtained through the aforementioned approach were presented and discussed. Reference | Related Articles | Metrics Select Additive manufactured trabecular-like Ti-6Al-4V scaffolds for promoting bone regeneration Wenbo Yang, Qing Han, Hao Chen, Yongyue Li, Xingchen Guo, Aobo Zhang, Yang Liu, Yifu Sun, Jincheng Wang J. Mater. Sci. Technol.    2024, 188: 116-130.   DOI: 10.1016/j.jmst.2023.10.061 Abstract （51）      PDF       Knowledge map    The Voronoi-tessellation method is a promising technique for porous implant design as it mimics the irregular structure of bone trabeculae very well. However, the optimal pore size distribution of Voronoi-based trabecular-like scaffolds (VBTSs) remains unknown. In this study, three VBTSs with different pore size distributions were fabricated by Electron-beam melting (EBM), with a regular cubic scaffold as a control. Compression experiments showed that the elastic modulus of all the fabricated scaffolds was within the range of human bone. The biocompatibility of the porous scaffolds was evaluated by Cell Counting Kit-8, live/dead staining, phalloidin staining, and scanning electron microscope. The effects of scaffolds on osteogenic differentiation were evaluated by alkaline phosphatase (ALP) assay, Alizarin Red S (ARS) assay, and Real-time quantitative polymerase chain reaction (RT-qPCR). In vivo experiments were performed to evaluate the performance of bone regeneration in the scaffolds. The results showed that all scaffolds were nontoxic with good biosafety, and VBTSs were more conducive to promoting cell proliferation, osteogenic differentiation, and bone regeneration within the scaffolds. Among the 596-1044 μm range, the VBTS with an average pore size of 596 μm performed best. This study showed that bone regeneration could be regulated by controlling the porous structure and provided a reference for applying VBTSs in bone implants. Reference | Related Articles | Metrics Select Gradient nanostructure, enhanced surface integrity and fatigue resistance of Ti-6Al-7Nb alloy processed by surface mechanical attrition treatment Hongwei Yang, Zichun Zhang, Jun Shu, Yong Han J. Mater. Sci. Technol.    2024, 188: 252-269.   DOI: 10.1016/j.jmst.2023.12.011 Abstract （44）      PDF       Knowledge map    Current Ti-based orthopedic implants often suffer from fatigue damage, therefore shortening their service lifespan. To solve this issue, in this study, mechanically polished Ti-6Al-7Nb (P-Ti6Al7Nb) was subjected to surface mechanical attrition treatment (SMAT). Effects of various SMAT process parameters, including ball diameter and treatment duration, on the surface integrity of P-Ti6Al7Nb were investigated, specifically in terms of surface quality, surface nanocrystalline layer, and residual stress. Subsequently, the microstructure, in-depth residual stress and microhardness distributions, surface roughness, and fatigue behavior in simulated body fluids of optimally SMATed Ti-6Al-7Nb (S-Ti6Al7Nb) were examined and compared to those of P-Ti6Al7Nb. Results showed that based on the experimental conditions established in the present research, the optimal parameters were determined to be a 3 mm ball diameter and a 15 min treatment duration, which resulted in excellent surface integrity; S-Ti6Al7Nb showed a 300 μm-thick gradient nanostructured layer comprising the thickest nanocrystalline layer of about 20 μm, a 1000 μm-deep residual compressive stress field with the maximum surface residual compressive stress, and a micro-concave topography but free of any defects or cracks. The microstructural evolution mechanism was also elucidated, revealing that the combination of multidirectional primary and secondary twins’ intersections and twin-dislocation interactions contributed to grain refinement. Compared to P-Ti6Al7Nb, S-Ti6Al7Nb exhibited a 40 % improvement in fatigue strength, owing to synergistic effects of the gradient nanostructured layer, surface work hardening, high amplitude of residual compressive stress, and improved surface integrity. These factors effectively prevented the initiation of fatigue crack at the surface and shifted it to the sublayer, and inhibited the subsequent crack propagation. Reference | Related Articles | Metrics Select Achieving large near-linear elasticity, low modulus, and high strength in a metastable β-Ti alloy by mild cold rolling Yu Fu, Wenlong Xiao, Jian Rong, Lei Ren, Huabei Peng, Yuhua Wen, Xinqing Zhao, Chaoli Ma J. Mater. Sci. Technol.    2024, 189: 1-12.   DOI: 10.1016/j.jmst.2023.11.066 Abstract （70）      PDF       Knowledge map    Simultaneously achieving high elasticity, low modulus, and high strength in Ti alloy has been a longstanding challenge. In this study, cold rolling was conducted to modulate the martensitic transformation of the Ti-15Nb-5Zr-4Sn-1Fe alloy to address this challenge. The 10% cold rolling process was primarily accommodated by a novel stress-induced sequential β-to-α′′-to-α? martensitic transformation accompanied by the disappearance of ω phase, which was sufficient to induce adequate martensite and defects to suppress the initial rapid stress-induced martensitic transformation, without destroying the equiaxed shape of prior β grains. Consequently, the novel sequential phase transformation led to a substantial decrease in Young's modulus by 50.5% while increasing the strength, resulting in an excellent combination of large near-linear elasticity of 2.34%, low modulus of 45 GPa, and high strength of 1093 MPa. The obtained large near-linear elasticity was mainly contributed by the concurrent low modulus and high strength obeying Hooke's law. These findings provide valuable insights into the attainment of concurrent high elasticity and low modulus in Ti alloys by regulating the stress-induced sequential martensitic transformation. Reference | Related Articles | Metrics Select Excellent tribocorrosion resistance of additively manufactured Ti-based heterogeneous composite coating via hardening and toughening effects Hongwei Zhang, Hongzhi Cui, Xiaojie Song, Kun Pang, Cheng Man, Feiya Liu, Xiaoying Wang, Zhongyu Cui J. Mater. Sci. Technol.    2024, 190: 76-92.   DOI: 10.1016/j.jmst.2023.11.027 Abstract （88）      PDF       Knowledge map    To improve the tribocorrosion resistance of oil drill pipes used in deep-sea drilling, a Ti-based composite coating was successfully fabricated by laser direct energy deposition technology on the TC4 titanium alloy surface. The microstructure analysis showed that a new heterogeneous structure of multistage strengthening phases (micron-sized TiN phases and nano-sized TiB phases) distributed on the β matrix (soft Cu-rich phases and hard Mo-rich phases) was formed, and the size of β grain was refined to 2 μm with the content of Cu higher than 12 wt.%. The microhardness of the composite coating was increased to more than 700 HV0.2 due to the solution strengthening of Mo elements and the formation of hard TiN phases. At the same time, the fracture toughness of 12Cu composite coating was significantly increased to 8.37 MPa m1/2, which was attributed to the combined effect of grain refining, high-density dislocations in Cu-rich phases, and nanoscale TiB phases. The synergistic enhancement of hardness and toughness of 12Cu composite coating promoted the generation of titano-molybdenum-copper composite oxide film on the worn surface, and the tribocorrosion resistance increased more than 7 times compared with TC4. 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