Investigation into the stress-strain compatibility and fracture behaviour of a TC18 titanium alloy with a multistage lamellar microstructure  

作　　者：Zhongxiang Li Zhaoxin Du Jun Cheng Zhiyong Yue Tianhao Gong Xudong Kang Yongcheng Zhu 

机构地区：[1]School of Materials Science and Engineering,Inner Mongolia University of Technology,Hohhot,010051,China [2]Collaborative Innovation Center of Non-ferrous Metal Materials and Processing Technology Co-constructed By the Province and Ministry,Inner Mongolia Autonomous Region,Inner Mongolia University of Technology,Hohhot,010051,China [3]Northwest Institute for Nonferrous Metal Research,Shanxi Key Laboratory of Biomedical Metal Materials,Xi'an,710016,China [4]School of Mechanical Engineering,Inner Mongolia University of Technology,Hohhot,010051,China

出　　处：《Progress in Natural Science:Materials International》2024年第5期1039-1048,共10页自然科学进展·国际材料(英文版)

基　　金：financially supported by the National Natural Science Foundation of China (No.52071185, No.52271249);Natural Science Foundation of Inner Mongolia (2024JQ03);Key research and Development Program of Shanxi(2023-YBGY-488);Basic scientific research business fee project for directly affiliated universities in Inner Mongolia Autonomous Region (JY20230108)

摘　　要：Understanding the fracture mechanism is essential for optimizing the mechanical properties of titanium alloys.The relationship between fracture behaviour and the multistage lamellar microstructure of the TC18(Ti–5Al–5Mo–5V–1Cr–1Fe) alloy was investigated via in situ tensile and three-point bending tests. The results indicate that the TC18 alloy, featuring a multistage lamellar microstructure(including a β matrix, primary lamellar α phase, bundles, and secondary lamellar α phase), exhibits an excellent combination of strength and ductility. The precipitation of the secondary lamellar α phase significantly enhances the alloy's strength but weakens the stress-strain compatibility of the microstructure. This results in a smaller crack-tip plastic zone(CTPZ) and causes dislocations to concentrate more at the grain boundaries and, to a lesser extent, at the phase interfaces. Consequently, in the later stages of crack propagation, microvoids and microcracks tend to form at dislocation pile-ups. With increasing stress, these microvoids and microcracks rapidly coalesce, leading to a greater proportion of intergranular fracture and thus reducing the fracture toughness of the alloy.

关 键 词：TC18titanium alloys In situ stretching Crack-tip plastic zone(CTPZ) Stress‒strain compatibility Fracture behaviour 

分 类 号：TG146.23[一般工业技术—材料科学与工程]