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China Welding 2020年第4期29卷 1-6页

作者： Zhang Hua Guo Qilong Zhao Changyu Lin Sanbao Shi Gongqi School of Mechanical Engineering Beijing Institute of Petrochemical TechnologyBeijing 102617China State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China The Welding Institute Cambridge CB216ALUK

3 mm thick 7050-T7451 aluminum alloy joint was obtained by friction stir welding, and the two-step aging treatment was performed at 121 ℃ × 5 h + 163 ℃× 27 h after welding. Microstructure, hardness profiles and stress corrosion sensitivity of the joint were measured and studied. The results indicate that through the two-step aging, the grain size is coarsened, the age-hardening precipitates and PFZ become wider at the same time, which results in the discontinuous grain boundary;the microhardness of the FSW joints decreased, but the heat-affected zone significantly narrowed, which increased the uniformity of the microhardness of the FSW joints;and the two-stage aging effectively reduced the stress corrosion sensitivity of the FSW joints. The joints with aging treatment were not broken after 60 days,however all the joints without aging treatment were broken within 1 day.

关键词： 7050 aluminum alloy friction stir welding two-step aging stress corrosion sensitivity

维普期刊数据库

Microstructure evolution and mechanical properties of Mg-x%Zn-1%Mn(x=4,5,6,7,8,9) wrought magnesium alloys

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Transactions of Nonferrous Metals Society of China 2011年第1期21卷 15-25页

作者：张丁非石国梁赵霞兵齐福刚重庆大学材料科学与工程学院重庆400045 国家镁合金材料工程技术研究中心重庆400044

The roles of Zn content and thermo-mechanical treatment in affecting microstructures and mechanical properties of Mg-x%Zn-1%Mn（mass fraction,x=4,5,6,7,8,9） wrought Mg alloys were *** microstructure was extremely refined by dynamic recrystallization（DRC） during *** increasing Zn content,the DRC grains tended to grow up,at the same time,more second phase streamlines would be present,which restricted the further *** solution treatment,the DRC grains would rapidly grow up;however,higher Zn content could hinder the grain boundary expanding,which results in finer ultimate ***2 dispersoid particles which are coherent with the matrix would precipitate from the supersaturated solid solution during the one-step aging process,and nano-sized GP zones formed during the pre-aging stage of the two-step aging provide a huge amount of effective nuclei for the MgZn2 phases formed in the second stage,which makes the MgZn2 particles much finer and more *** mechanical properties of as-extruded samples were not so sensitive to the variation of Zn content,the tensile strength fluctuates between 300 and 320 MPa,and the elongation maintains a high value between 11% and 14%.The strength of aged samples rises as a parabolic curve with increasing Zn content,specifically,the tensile strength of one-step aged samples rises from 278 to 374 MPa,and that of two-step aged ones rises from 284 to 378 MPa,yet the elongation of all aged samples is below 8%.When Zn content exceeds its solid solution limit in Mg-Zn system（6.2%,mass fraction）,the strength rises slowly but the elongation deteriorates sharply,so a Mg-Zn-Mn alloy with 6% Zn possesses the best mechanical properties,that is,the tensile strengths after one-and two-step aging are 352 and 366 MPa,respectively,and the corresponding elongations are 7.98% and 5.2%,respectively.

关键词： Mg-Zn-Mn alloy two-step aging age-hardening Zn content

维普期刊数据库

Heterogeneous precipitate microstructure in titanium alloys for simultaneous improvement of strength and ductility

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Journal of Materials Science & Technology 2022年第29期124卷 150-163页

作者： Mengyuan Hao Pei Li Xuexiong Li Tianlong Zhang Dong Wang Qiaoyan Sun Libin Liu Jinshan Li Yuyou Cui Rui Yang Dongsheng Xu Frontier Institute of Science and Technology State Key Laboratory for Mechanical Behavior of MaterialsXi’an Jiaotong UniversityXi’an 710049China Institute of Metal Research Chinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering Central South UniversityChangsha 410083China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China Thermal Power Research Institute Co.Ltd. Xi’an 710032China

The design of alloys with simultaneous high strength and high ductility is still a difficult ***,we propose a new approach to designing multi-phase alloys with a synergistic combination of strength and ductility by engineering heterogeneous precipitate microstructures through the activation of different transformation *** a two-phase titanium alloy as an example,phase field simulations are carried out firstly to design heat treatment schedules that involve both conventional nucleation and growth and non-conventional pseudospinodal decomposition mechanisms,and the calculated microstructures have been evaluated by crystal plasticity finite element *** to simulations,we then set a two-step heat treatment to produce bimodalα+βmicrostructure in *** mechanical testing shows that the ductility of the alloy is increased by~50%and the strength is increased by~10%as compared to its unimodal *** work may provide a general way to improve the mechanical properties of alloys through multiscale microstructure design.

关键词： Titanium alloys Phase field simulation Crystal plasticity finite element two-step aging Pseudospinodal decomposition mechanisms Multiscale heterogeneous microstructure

维普期刊数据库

Microstructure evolution and corresponding tensile properties of Ti–5Al–5Mo–5V–1Cr–1Fe alloy controlling by multi-heat treatments

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Progress in Natural Science:Materials International 2021年第5期31卷 731-741页

作者： Zedong Liu Zhaoxin Du Hanyu Jiang Tianhao Gong Xiaoming Cui Jingwen Liu Jun Cheng School of Materials Science and Engineering Inner Mongolia University of Technology Inner Mongolia Key Laboratory of Light Metal Materials Inner Mongolia University of Technology Northwest Institute for Non-ferrous Metal Research Shaanxi Key Laboratory of Biomedical Metal Materials

The effects of microstructure morphology on corresponding tensile mechanical properties of Ti–5Al–5Mo–5V–1Cr–1Fe alloy controlling by three different heat treatment conditions (solution,single-step and two-step aging) were investigated in the present *** results show that the solution temperature exhibited an important impact on the precipitation behavior of secondary-αphase (αs) during aging,in which the content ofαsgradually increased with the increase of solution *** the alloy was single-step aged at500–600~°C,the needle-likeαsprecipitated from matrix,as well as the content ofαsdecreased and coarsened corresponding to the increase of aging *** with single-step aging,theαsslightly increased when the alloy was subjected to two-step aging heat *** tensile results show that theαsis the main strengthening phase in the ***,its content as well as the intensity of the precipitation mode directly affects the strength,whereas inevitably with an accompanying penalty on *** general,the higher solution temperature and the lower first-step aging temperature result in a more intensiveαsand then lead to the higher ***,{10■2}and{10■1}twins were found in two-step aged tensile samples,which may impart twinning-induced plasticity (TWIP).Overall,this study demonstrates that the alloy can be heat treated to achieve an excellent match between strength and ductility and to provide sufficient stress and optional ductility(ultimate strength of 978–1439 MPa and elongation of 8.25–18.9%).

关键词： Titanium alloy Heat treatment two-step aging Microstructures Tensile properties Twins