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| 1 | Effect of Heat Treatment on Cu Distribution,Antibacterial Performance and Cytotoxicity of Ti-6Al-4V-5Cu Alloy显示文摘A copper-bearing Ti-6AI-4V-5Cu alloy was processed and subjected to different heat treatments to explore the relationship among microstructure,antibacterial performance,and cytocompatibility.Characterization of microstructure revealed that the solution treated alloy consisted of α phase,α' phase and(3 phase,while besides these phases,the aged alloy also contained the precipitations of intermetallic Ti_2Cu compound.The solution treated alloy showed better antibacterial performance with increasing the solution temperature.The Cu ions released from Ti—6AI—4V—5Cu alloy could effectively inhibit the formation of bacterial biofilm on the surface of alloy,and do not induce any cytotoxicity.The optimal heat treatment for Ti-6Al-4V-5Cu alloy was solution treated at 930 C,at which it could exhibit both promising antibacterial performance and no cytotoxicity. | Zheng Ma Ling Ren Rui Liu Ke Yang Yu Zhang Zhenhua Liao Weiqiang Liu Min Qi R.D.K.Misra | 2015 | Journal of Materials Science & Technology2015，31，7： | 10 |
| 2 | Optimizing the low-pressure carburizing process of 16Cr3NiWMoVNbE gear steel显示文摘Compared with the traditional atm ospheric carburization, low-pressure carburization has the benefits of producing no surface oxidation and leaving fine, uniformly dispersed carbides in the carburized layer. However, the process param eters for low-pressure carburization of 16Cr3NiWMoVNbE steel have yet to be optimized. Thus, we use the saturation-value method to optimize these parameters for aviation-gear materials. Toward this end, the m icrostructure and properties of 16Cr3NiWMoVNbE steel after different carburization processes are studied by optical microscopy, scanning electron microscopy, transm ission electron microscopy, and electron probe microanalysis. Considering the saturated austenite carbon concentration, we propose a model of carbon flux and an alloy coefficient for low -pressure carburization to reduce the carbon concentration in austenite and avoid the surface carbide network. At the early stage of carburization (30 s), the gas-solid interface has a higher concentration gradient. The averaging method is not ideal in practical applications, but the carbon flux measured by using the segm ented average m ethod is 2.5 times that measured by the overall average method, which is ideal in practical applications. The corresponding carburization tim e is reduced by 60%. By using the integral average method, the actual carburization time increases, which leads to the rapid form ation of carbide on the surface and affects the entire carburization process. Nb and Wcombine with C to form carbides, which hinders carbon diffusion and consumes carbon, resulting in a sharp decrease in the rate of C diffusion in austenite (the diffusion rate is reduced by 52% for 16Cr3NiWMoVNbE steel). By changing the diffusion coefficient model and comparing the hardness gradient of different processes, the depth of the actual layer is found to be very similar to the design depth. | Haojie Wang Bin Wang Zhaodong Wang Yong Tian R.D.K.Misra | 2019 | Journal of Materials Science & Technology2019，35，7： | 9 |
| 3 | Macro to nanoscale deformation of transformation-induced plasticity steels:Impact of aluminum on the microstructure and deformation behavior显示文摘This work aims to elucidate the impact of aluminum-content on microstructure and deformation mechanisms of transformation-induced plasticity(TRIP) steels through macroscale and nanoscale deformation experiments combined with post-mortem electron microscopy of the deformed region.The solid-state transformation-induced mechanical deformation varied with the Al contents,and influenced tensile strength-ductility combination.Steels with 2–4 wt% Al were characterized by TRIP effect.In contrast to 2 Al-TRIP and 4 Al-TRIP steels,twinning-induced plasticity(TWIP) was also observed in conjunction with strain-induced martensite in 6 Al-TRIP steel.This behavior is attributed to the increase in stacking fault energy with the increase of Al content and stability of austenite,which depends on the local chemical variation.The study addresses the knowledge gap with regard to the effect of Al content on austenite stability in medium-Mn TRIP steels.This combination is expected to potentially enable cost-effective alloy design with high strength-high ductility condition. | V.S.Y.Injeti Z.C.Li B.Yu R.D.K.Misra Z.H.Cai H.Ding | 2018 | Journal of Materials Science & Technology2018，34，5： | 7 |
| 4 | Effects of Nb and V on Microstructural Evolution,Precipitation Behavior and Tensile Properties in Hot-rolled Mo-bearing Steel显示文摘Microstructural evolution,precipitation behavior,and tensile properties of four experimental Mo-bearing steels were studied to elucidate the effects of Nb and V on microstructural properties.The results indicated that the microstructure of hot-rolled steels consisted of polygonal ferrite and degenerate pearlite,and the morphology remained same after holding at 600 ℃for 1h.The smallest grain size was obtained in Nb-V-Mo containing steel,followed by Nb-Mo and V-Mo steels.Precipitation was less in the hot-rolled Mo-bearing steel.The maximum volume fraction of precipitates was obtained in Nb-V-Mo bearing steel,and the Nb-V-Mo complex carbonitrides were highly stable at 600℃.In the Mo-bearing steel,the yield ratio was lowest at room temperature but highest at 600℃,which was attributed to the precipitation of Mo carbides and drag effect of Mo solute on dislocation movement. | Fu-ming LIU Jian-jun WANG Yu-jie LIU R.D.K.MISRA Chun-ming LIU | 2016 | Journal of Iron and Steel Research(International)2016，23，6： | 6 |
| 5 | Grain boundary and microstructure engineering of Inconel 690 cladding on stainless-steel 316L using electron-beam powder bed fusion additive manufacturing显示文摘This research explores the prospect of fabricating a face-centered cubic(fcc) Ni-base alloy cladding(Inconel 690) on an fcc Fe-base alloy(316 L stainless-steel) having improved mechanical properties and reduced sensitivity to corrosion through grain boundary and microstructure engineering concepts enabled by additive manufacturing(AM) utilizing electron-beam powder bed fusion(EPBF). The unique solidification and associated constitutional supercooling phenomena characteristic of EPBF promotes[100] textured and extended columnar grains having lower energy grain boundaries as opposed to random, high-angle grain boundaries, but no coherent {111} twin boundaries characteristic of conventional thermo-mechanically processed fcc metals and alloys, including Inconel 690 and 316 L stainless-steel.In addition to [100] textured grains, columnar grains were produced by EPBF fabrication of Inconel 690 claddings on 316 L stainless-steel substrates. Also, irregular 2–3 μm diameter, low energy subgrains were formed along with dislocation densities varying from 108 to 109 cm^2, and a homogeneous distribution of Cr_(23)C_6 precipitates. Precipitates were formed within the grains(with ~3 μm interparticle spacing),but not in the subgrain or columnar grain boundaries. These inclusive, hierarchical microstructures produced a tensile yield strength of 0.527 GPa, elongation of 21%, and Vickers microindentation hardness of 2.33 GPa for the Inconel 690 cladding in contrast to a tensile yield strength of 0.327 GPa, elongation of 53%, and Vickers microindentation hardness of 1.78 GPa, respectively for the wrought 316 L stainlesssteel substrate. Aging of both the Inconel 690 cladding and the 316 L stainless-steel substrate at 685?C for50 h precipitated Cr_(23)C_6 carbides in the Inconel 690 columnar grain boundaries, but not in the low-angle(and low energy) subgrain boundaries. In contrast, Cr_(23)C_6 carbides precipitated in the 316 L stainless-steel grain boundaries, but not in the low energy coherent {111} twin boundaries. Consequently, the Inconel690 subgrain boundaries essentially serve as surrogates for coherent twin boundaries with regard to avoiding carbide precipitation and corrosion sensitization. | I.A.Segura L.E.Murr C.A.Terrazas D.Bermudez J.Mireles V.S.V.Injeti K.Li B.Yu R.D.K.Misra R.B.Wicker | 2019 | Journal of Materials Science & Technology2019，35，2： | 5 |
| 6 | 不同固溶方式对Al-Mg-Si合金组织性能及析出行为的影响(英文)显示文摘采用扫描电镜、透射电镜、拉伸试验及差示扫描量热技术研究不同固溶方式对Al-Mg-Si合金组织性能和析出行为的影响。结果表明:热风固溶比电阻固溶的合金再结晶晶粒更加均匀细小。经两种方式固溶后,合金织构不同,电阻固溶产生更多旋转立方织构,有利于提高合金的成形性。冲压前,均匀细小晶粒和基体中大量团簇存在使热风固溶合金强度较高。烤漆时,更多团簇发生转变,同时具有较好的烤硬化性。 | 高冠军 贺晨 李勇 李家栋 王昭东 R.D.K.MISRA | 2018 | Transactions of Nonferrous Metals Society of China2018，28，5： | 5 |
| 7 | High strength-superplasticity combination of ultrafine-grained ferritic steel:The significant role of nanoscale carbides显示文摘There is currently a gap in our understanding of mechanisms that contribute to high strength and high plasticity in high strength UFG ferritic steel with nano-size Fe3 C carbides in situations that involve combination of various strain rates and high temperature.In this regard,we describe the mechanistic basis of obtaining high strength-high plasticity combination in an ultrafine-grained(UFG)(~500±30 nm)ferritic steel with nano-size carbides,which sustained large plastic deformation,exceeding 100%elongation at a temperature significantly below 0.5 of the absolute melting point(Tm).To address the missing gap in our knowledge,we conducted a series of experiments involving combination of strain rate and temperature effects in conjunction with electron microscopy and atom probe tomography(APT).Strain rate studies were carried out at strain rates in the range of 0.0017-0.17 s^(-1)and at different temperatures from 25℃to 600℃.Dynamic recrystallization occurred at 600℃,resulting in a significant decrease in yield and tensile strength.Nevertheless,the UFG ferritic steels had an advantage in tensile strength(UTS)and elongation-to-failure(εf)at 600℃,especially at strain rate of 0.0017 s^(-1),with high UTSof 510 MPa and excellent low temperature(<0.42 Tm)superplasticity(εf=110%).These mechanical properties are significantly superior compared to similar type of steels at identical temperature.A mechanistic understanding of mechanical behavior of UFG ferritic steels is presented by combining the effect of strain rate,temperature,and nano-size carbides. | J.W.Liang Y.F.Shen R.D.K.Misra P.K.Liaw | 2021 | Journal of Materials Science & Technology2021，，24： | 5 |
| 8 | Significant effect of as-cast microstructure on texture evolution and magnetic properties of strip cast non-oriented silicon steel显示文摘In this study, two types of as-cast microstructure produced by strip casting were cold rolled and annealed to investigate the effect of initial microstructure on the textural evolution and magnetic properties of non-oriented silicon steel. The results indicated that the cold-rolled sheets of coarse-grained strip with pronounced {100} components exhibited stronger 入 fiber(<100>//ND) and weaker γ fiber(<111>//ND)texture as composed to the fine-grained strip with strong Goss({110}(001)) texture. After annealing, the former was dominated by η fiber(<001>//RD) texture with a peak at {110}<001)orientation, while the latter consisted of strong {111}(112) and relatively weak {110}(001) texture. In addition, a number of precipitates of size ~30-150 nm restricted the grain growth during annealing, resulting in recrystallization of grain size of ~46 μm in the coarse-grained specimen and ~41μm in the fine-grained specimen.Ultimately, higher magnetic induction(~1.72 T) and lower core loss(~4.04 W/kg) were obtained in the final annealed sheets of coarse-grained strip with strong {100} texture. | Haitao Jiao Yunbo Xu Wenzheng Qiu Haijie xu R.D.K.Misra Yifeng Du Jianping Li Guodong Wang | 2018 | Journal of Materials Science & Technology2018，34，12： | 4 |
| 9 | Hot Deformation Behavior and Processing Maps of a High Al-low Si Transformation-Induced Plasticity Steel: Microstructural Evolution and Flow Stress Behavior显示文摘Hot deformation behavior of a high Al-low Si transformation-induced plasticity(TRIP) steel was studied by an MMS-300 thermo-simulation machine at the temperature range of 1050–1200℃ and strain rate range of 0.01–10s^(-1). The constitutive equations of the TRIP steel were established at high temperature by fitting the strain factor with a sixth-order polynomial. The instability during hot rolling was discussed using processing maps. The results reveal that two types of flow stress curves(dynamic recrystallization and dynamic recovery) were observed during the hot compression of the high Al-low Si TRIP steel. Flow stress decreased with increasing deformation temperature and decreasing strain rate. The predicted flow stress of experimental TRIP steel is in agreement with the experimental values with an average absolute relative error of 4.49% and a coefficient of determination of 0.9952. According to the obtained processing maps, the TRIP steel exhibits a better workability at strain rate of 0.1s^(-1) and deformation temperature of 1200℃ as compared to other deformation conditions. | H.Q.Huang H.S.Di N.Yan J.C.Zhang Y.G.Deng R.D.K.Misra J.P.Li | 2018 | Acta Metallurgica Sinica(English Letters)2018，31，5： | 3 |
| 10 | Effect of pre-annealing prior to cold rolling on the precipitation,microstructure and magnetic properties of strip-cast non-oriented electrical steels显示文摘A novel processing route involving strip casting, pre-annealing treatment, cold rolling and recrystallization annealing was applied to a Fe-2.6%Si steel to improve the magnetic properties. The impact of as-cast strip pre-annealing on the microstructure, texture, precipitation and magnetic properties were investigated by electron probe micro-analysis, transmission electron microscopy, and X-ray diffraction analysis,etc. It was found that the precipitation of second-phase particles during strip casting was restrained by rapid solidification. The absence of pre-annealing led to the occurrence of a large amount of 20–50 nm Mn S precipitates in the final annealed sheets, which is responsible for fine grains and high core loss(4.01 W/kg) due to grain boundary pinning effect. Although the microstructure and texture of 900–1000?C pre-annealed samples were similar to those of as-cast strip, significant grain coarsening together with the strengthening of-fiber texture was observed in the 1100?C pre-annealed strips. In comparison with the case of as-cast strip, a higher amount of large-sized precipitates consisting of manganese sulfide and/or aluminum nitride occurred in matrix after pre-annealing. Correspondingly, in the final annealed sheets, the number density of precipitates with sizes smaller than 100 nm was substantially reduced, and100–200 nm and 200–500 nm sized particles became more dominant in samples subjected to 30-min and 120-min pre-annealing treatments respectively. In addition, the average grain size of final annealed sheets increased with the pre-annealing temperature and time because of the weakened pining effect of coarsen precipitates. Ultimately, the magnetic induction of samples subjected to pre-annealing was slightly increased and ranged from 1.73 T to 1.75 T owing to the enhancement of {100} recrystallization texture, and simultaneously the core loss significantly decreased until a minimum of 3.26 W/kg was reached. Nevertheless, large number of 200–500 nm particles presented during pre-annealing for 120 min could weaken the improvement in core loss which is likely associated with the pinning effect on magnetic domain wall. | Yunbo Xu Haitao Jiao Yuanxiang Zhang Feng Fang Xiang Lu Yang Wang Guangming Cao Chenggang Li R.D.K.Misra | 2017 | Journal of Materials Science & Technology2017，33，12： | 3 |
| 11 | Corrosion Behavior of High-Strength Steel for Flexible Riser Exposed to CO_2-Saturated Saline Solution and CO_2-Saturated Vapor Environments显示文摘The corrosion behavior of high-strength steel used for flexible riser exposed to CO_(2-)saturated saline solution and CO_(2-) saturated vapor environments was studied through immersion experiment and electrochemical corrosion experiment. The corrosion behavior and mechanism of the tested steel were analyzed on the basis of corrosion kinetics, nature of corrosion products, corrosion product morphology, elemental distribution and polarization curves. The experimental results showed that the microstructure of the tested steel was bainitic microstructure. The corrosive activity of the tested steel exposed to CO_(2-) saturated vapor environment was significantly lower than that exposed to CO_(2-) saturated saline solution environment.On prolonging the exposure time, the corrosion rate gradually decreased, the corrosion heterogeneity increased, and the dimensions of FeCO_3 crystals gradually became small. At later stages of corrosion, the corrosion current density decreased significantly and the anodic Tafel slope increased, indicating that the corrosion process was strongly inhibited. The corrosion mechanism of low-alloy steel with bainitic microstructure was proposed based on experimental results. | Da-Zheng Zhang Xiu-Hua Gao Lin-Xiu Du Hong-Xuan Wang Zhen-Guang Liu Ning-Ning Yang R.D.K.Misra | 2019 | Acta Metallurgica Sinica(English Letters)2019，32，5： | 2 |
| 12 | Characterization of Microstructure and Texture in Grain-Oriented High Silicon Steel by Strip Casting显示文摘面向谷物的 4.5wt% Si 和 6.5wt% Si 钢被长带扔生产,温暖的滚动,冷滚动,主要退火,并且第二等的退火。高斯谷物足够地被发展并且盖住第二等的重新使结晶的表的全部表面。微观结构和质地被 OM, EBSD, TEM,和 XRD 描绘。这被观察在在 700 素 ? 滚动以后 ????????G 牡笠ㄠ素ㄠ吗?? | Xiang Lu Yun-Bo Xu Feng Fang Yuan-Xiang Zhang Yang Wang Hai-Tao Jiao R.D.K.Misra Guang-Ming Cao Cheng-Gang Li Guo-Dong Wang | 2015 | Acta Metallurgica Sinica(English Letters)2015，28，11： | 2 |
| 13 | Structure-property relationships in heat-affected zone of gas-shielded arc-welded V-N microalloyed steel显示文摘The structure-property relationship in heat-affected zone (HAZ)of a low-carbon steel bearing V-N subjected to gasshielded arc welding was explored.The microstructural characteristics of base metal (BM),coarse-grained HAZ (CGHAZ),fine-grained HAZ,and intercritical HAZ were significantly different.The effect of grain-refinement strengthening and transformation hardening on HAZ contributed to equivalent hardness of 260.8-278.5 HV in comparison with BM hardness of 272.0 HV.Moreover,excellent impact toughness at -20 ℃ was obtained because of high resistance to crack propagation by high-misorientation boundaries,leading to impact fracture consisting of dimples.In CGHAZ,free N was partly fixed by V(C,N)precipitates,such that the deterioration effect of N on toughness was considered to be nearly eliminated.In comparison with CGHAZ,weld metal contained higher fraction of acicular ferrite with fine plates,while the impact toughness was inferior because of the detrimental influence of coarse inclusions from the welding wire.The nanoscale V(C,N)precipitates in CGHAZ had weak effect on toughness because of small size. | Jun Hu Lin-xiu Du Bin Zhang Xiang-yu Qi Xiu-hua Gao R.D.K.Misra | 2018 | Journal of Iron and Steel Research(International)2018，25，12： | 1 |
| 14 | Microstructural refinement mechanism and its effect on toughness in the nugget zone of high-strength pipeline steel by friction stir welding显示文摘High-strength pipeline steel was subjected to friction stir welding(FSW)at rotation rates of 400-700 rpm,and the grain refinement mechanism of the nugget zone(NZ)was determined.The thermomechanical process during FSW in the NZ was simulated by multi-pass thermal compression,thereby achieving the austenitic non-recrystallization temperature(T_(nr)).The austenitic non-recrystallization in the NZ at the lowest rotation rate of 400 rpm caused a significant grain refinement.Furthermore,the reduced rotation rate also resulted in the formation of a high ratio of island-like martensite-austenite(M-A)constituent.The toughness of the NZs was enhanced as the rotation rate decreased,which is attributed to the fine effective grains and homogeneously distributed fine M-A constituents dramatically inhibiting crack initiation and propagation. | R.H.Duan G.M.Xie P.Xue Z.Y.Ma Z.A.Luo C.Wang R.D.K.Misra | 2021 | Journal of Materials Science & Technology2021，，34： | 1 |
| 15 | Highly ductile hypereutectic Al-Si alloys fabricated by selective laser melting显示文摘In the endeavor to maximize the refinement effect of primary Si and alleviate the inherent brittleness of hypereutectic Al-Si alloy,the approach of coating P as a modifier on powder was adopted.The ultimate aim was to create more heterogeneous fine Al P nucleus and enhance the nucleation efficiency of primary Si on Al P to refine the coarse primary Si to nano-scale during 3D printing.In the combination of large undercooling and high density of nucleation sites,the size of primary Si was successfully refined to 200–300 nm and the divorced eutectic was also induced to modify the microstructure of matrix.In the presence of nano-scale primary Si,the melting pool boundary(MPB)feature disappeared and the fracture mechanism also changed from load transfer to interfacial fracture.Compared with the pristine alloy,the ductility was increased four times without significantly changing the ultimate tensile strength(UTS)and wear resistance.The improvement of ductility is attributed to the refinement of primary Si,the disappearance of MPB features and the formation of divorced eutectic.The optimal tensile properties were:UTS-482 MPa,yield strength-320 MPa and ductility of 8.1%at 0.05 wt.%P.These are comparable to those for high-strength Al alloys. | Yafeng Yang Kang Geng Shaofu Li Michael Bermingham R.D.K.Misra | 2022 | Journal of Materials Science & Technology2022，，15： | 1 |
| 16 | Softening and recrystallization behavior of a new class of ferritic steel显示文摘In order to clarify the recrystallization mechanism of low-densityδ-ferrite steel Fe-4AI-2Ni,interrupted and single-pass compression tests were carried out.In this regard,five deformation temperatures(750-950 at an interval of 50°C)and different hold time were selected.It was observed that the softening and recrystallization fraction was enhaneed with increased deformation temperature and hold time.The original grain bounclaries were the preferred nucleation sites for recrystallized grains,and recrystallization had an impact on obtaining homogeneous and fine-grained structure.Recrystallization in the ferritic alloy commenced after a significant degree of softening,and the softening associated with recovery was appreciably less.The optimum rolling deformation temperature was identified to be greater than 900°C. | Xiang-yu Xu Jian-zhe Li Xue-min Wang Wei Zhang Qian-nan Liu Cheng-jia Shang R.D.K.Misra | 2019 | Journal of Iron and Steel Research(International)2019，26，2： | 1 |
| 17 | Effect of Ca on microstructure and high temperature creep properties of AM60-1Ce alloy显示文摘A series of AM60-1Ce-xCa(x=0, 0.5, 1.5, 2.5) magnesium alloys were prepared by gravity casting method and analyzed by means of XRD, DSC and SEM. The effects of Ca on normal temperature mechanical properties and high temperature creep behavior of alloys were characterized by tensile and constant creep test.Microstructure analysis indicated that Ca was preferentially combined with Al in the alloy to form the high melting point Al_2Ca phase at the grain boundary. The addition of Ca can refine the crystal grains and reduces the content of β-Mg_(17)Al_(12) phase. With the increase of Ca content in the alloy, Al_2Ca phases at the grain boundary gradually changed to the network of lamellar structure, and replaced the β-Mg_(17)Al_(12) phase as the main strengthening phase gradually. The creep resistance of the alloy continuously increases because the high-temperature stable phase Al_2Ca firmly nailed at grain boundaries impedes the sliding of grain boundaries. However, when the addition of Ca was more than 1.5%, mechanical properties of the alloy started to decrease, which was probably due to the large amount of irregularly shaped Al_2Ca phases at the grain boundary. Experimental results show that the optimal addition amount of Ca is 1.5 wt.%. | Wei Jin Yu-lai Song Yao-hui Liu Ping Zhao R.D.K.Misra | 2019 | China Foundry2019，16，2： | 1 |
| 18 | Electrochemical behavior of open-cellular structured Ti-6Al-4V alloy fabricated by electron beam melting in simulated physiological fluid:the significance of pore characteristics显示文摘The cellular structured titanium alloys have attracted significant attention for implants because of their lower Young’s modulus,which is comparable to human bone and has the capability of providing space for bone tissue in-growth.However,there is a gap in the knowledge in regard to the relationship between the pore characteristics and the electrochemical performance of open-cellular structured titanium alloys.In this study,we elucidate the influence of pore characteristics on the electrochemical performance of open-cellular structured Ti-6Al-4V alloys produced by electron beam melting(EBM).Intriguingly,the passive film formed on cellular structured Ti-6Al-4V alloy with a larger pore size was more stable and protective,and the corrosion performance was superior compared to the samples with a smaller pore size in phosphate buffered saline(PBS),mainly because of relatively smaller exposed surface area and unlimited flow of electrolyte.However,in acidic PBS containing fluoride ions,the pore characteristics did not play an important role in the corrosion resistance.It was considered that the protective film breaks down such that the corrosion performance of cellular structured alloys was comparable to each other in this harsh environment. | Xin Gai Rui Liu Yun Bai Shujun Li Yang Yang Shenru Wang Jianguo Zhang Wentao Hou Yulin Hao Xing Zhang Rui Yang R.D.K.Misra | 2022 | Journal of Materials Science & Technology2022，，2： | 1 |
| 19 | Machine learning guided automatic recognition of crystal boundaries in bainitic/martensitic alloy and relationship between boundary types and ductile-to-brittle transition behavior显示文摘Gradient boosting decision tree(GBDT)machine learning(ML)method was adopted for the first time to automatically recognize and conduct quantitative statistical analysis of boundaries in bainitic microstructure using electron back-scatter diffraction(EBSD)data.In spite of lack of large sets of EBSD data,we were successful in achieving the desired accuracy and accomplishing the objective of recognizing the boundaries.Compared with a low model accuracy of<50%as using Euler angles or axis-angle pair as characteristic features,the accuracy of the model was significantly enhanced to about 88%when the Euler angle was converted to overall misorientation angle(OMA)and specific misorientation angle(SMA)and considered as important features.In this model,the recall score of prior austenite grain(PAG)boundary was~93%,high angle packet boundary(OMA>40°)was~97%,and block boundary was~96%.The derived outcomes of ML were used to obtain insights into the ductile-to-brittle transition(DBTT)behavior.Interestingly,ML modeling approach suggested that DBTT was not determined by the density of high angle grain boundaries,but significantly influenced by the density of PAG and packet boundaries.The study underscores that ML has a great potential in detailed recognition of complex multi-hierarchical microstructure such as bainite and martensite and relates to material performance. | X.C.Li J.X.Zhao J.H.Cong R.D.K.Misra X.M.Wang X.L.Wang C.J.Shang | 2021 | Journal of Materials Science & Technology2021，，25： | 1 |
| 20 | The effect of different coatings on bone response and degradation behavior of porous magnesium-strontium devices in segmental defect regeneration显示文摘Regeneration of long-bone segmental defects remains a challenge for orthopedic surgery.Current treatment options often require several revision procedures to maintain acceptable alignment and achieve osseous healing.A novel hollow tubular system utilizing magnesium-strontium(Mg-Sr)alloy with autogenous morselized bone filled inside to repair segmental defects was developed.To improve the corrosion and biocompatible properties,two coatings,Ca-P and Sr-P coatings,were prepared on surface of the implants.Feasibility of applying these coated implants was systematically evaluated in vitro and in vivo,and simultaneously to have a better understanding on the relationship of degradation and bone regeneration on the healing process.According to the in vitro corrosion study by electrochemical measurements,greater corrosion resistance was obtained for Ca-P coated sample,and attributed to the double-layer protective structure.The cytotoxicity and alkaline phosphatase(ALP)assays demonstrated enhanced bioactivity for Sr-P coated group because of the long-lasting release of beneficial Sr^(2+).At 12 weeks post-implantation with Mg-Sr alloy porous device,the segmental defects were effectively repaired with respect to both integrity and continuity.In addition,compared with the Ca-P coated implant,the Sr-P coated implant was more proficient at promoting bone formation and mineralization.In summary,the Sr-P coated implants have bioactive properties and exceptional durability,and promote bone healing that is close to the natural rate,implying their potential application for the regeneration of segmental defects. | Nan Zhang Weidan Wang Xiuzhi Zhang Krishna.C.Nune Ying Zhao Na Liu R.D.K.Misra Ke Yang Lili Tan Jinglong Yan | 2021 | Bioactive Materials2021，6，6： | 1 |
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