Atomistic simulation of crack propagation along γ-TiAl lamellar interface

Joint 5th International Conference on Advances in Solidification Processes;5th International Symposium on Cutting Edge of Computer Simulation of Solidification, Casting and Refining

土木建筑工程;计算机科学

Li, W.^1^2 ; Nan, H.^2 ; Qian, X.W.^1 ; Yin, Y.J.^1 ; Xu, Q.^1 ; Shen, X.^1 ; Yu, W.^1^2 ; Feng, X.^2 ; Zhu, L.P.^2 ; Zhou, J.X.^1

State Key Laboratory of Materials Processing and Die and Mould Technology, Huazhong University of Science and Technology, Wuhan

430074, China^1

AECC Beijing Institute of Aeronautical Materials, Beijing

100095, China^2

关键词: Atomistic simulations;    Classical molecular dynamics;    Constant strain rate;    Cyclic mechanical loading;    Evolution of cracks;    Propagation mechanism;    Shockley dislocations;    Structural component;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/529/1/012042/pdf
DOI  :  10.1088/1757-899X/529/1/012042

来源: IOP

【 摘 要 】

Due to start-up and shut-down operations of engine, TiAl structural components usually undergo not only static but also cyclic mechanical loading. The crack propagation mechanisms of γ-TiAl under two types of loading are studied in this work to reveal the differences of the mechanisms under constant strain rate and cyclic loading. Since the crack prefers to nucleate at the interface, two types of loadings are applied to a γ-TiAl interface system with a pre-existing micro-crack at the interface by the means of classical molecular dynamics simulation, the loading direction is along [111] perpendicular to the interface. The evolution of crack tip and dislocation is observed in atomistic scale. The results show that, under both loading types, the crack propagates asymmetrically, Shockley dislocations emit on the (-1-11) slip plane from the right crack tip and slip along [-1-1-2] direction. The dislocations blunt the extension of crack while the left crack tip propagates in a brittle way. During the cyclic loading, different with constant strain rate condition, the crack advances and dislocations slip with increasing loads and retreat during unloading. In addition, the stress decreases and the crack length increases with the increase of the cyclic loading number.