温度对单晶γ-TiAl合金裂纹扩展的影响的分子动力学模拟  

Molecular Dynamics Simulation of Temperature Effect on Crack Propagation for Single Crystal γ-TiAl Alloy

作　　者：曹卉[1,2] 芮执元[1,2] 罗德春[1,2] 付蓉[1,2] 剡昌锋[1,2] 

机构地区：[1]兰州理工大学机电工程学院,甘肃兰州730050 [2]兰州理工大学数字制造技术与应用省部共建教育部重点实验室,甘肃兰州730050

出　　处：《材料科学与工程学报》2016年第4期607-613,共7页Journal of Materials Science and Engineering

基　　金：国家自然科学基金资助项目(51065014);甘肃省自然科学基金资助项目(148RJZA008);甘肃省高等学校科研资助项目(2014A-033)

摘　　要：用分子动力学方法从原子尺度对单晶γ-TiAl合金中心裂纹的扩展机理进行了研究,模拟了不同温度下预制中心裂纹的扩展过程。结果表明:随着温度升高,裂纹的启裂时间变长,启裂应力值分别为5.64GPa、4.58GPa和4.27GPa;裂尖和边界发射的位错数目随温度的升高而增多;温度为300K时,裂纹先脆性扩展,出现分枝后,裂纹通过裂尖发射位错向前扩展,扩展过程为塑性扩展;温度达750K时裂纹出现分枝,扩展过程为塑性扩展,此时的裂纹扩展速率慢于300K时的裂纹扩展速率;950K时裂纹没有出现分枝,扩展过程为塑性扩展且扩展速率最快;三种温度下裂纹扩展过程均出现裂尖钝化与偏折现象。Molecular dynamics simulation was performed to study the center crack propagation process in single crystal γ-TiAl at different temperatures on the atomic scale. The results show that., as temperature increased, the time of starting crack propagation increased and the crack starting stresses were 5.64GPa, 4. 58GPa and 4. 27GPa for the temperatures of 300K, 750K and 950K, respectively. Crack tip and boundary emitted more dislocations with temperature increased. At 300K, the crack propagated in a brittle cleavage manner at first. After emergence of branch, the crack propagated in a plastics manner and accompanied with emission dislocations. Branch also appeared at 750K, crack propagated in plastics manner and crack propagated more quickly than that at 300k. There were no branch manner, the rate of crack propagation was the fastest occurred throughout the process of crack propagation. appeared at 950K and crack also propagated in plastics of all. The phenomenon of tip blunting and deflection

关 键 词：Γ-TIAL合金 单晶 分子动力学 位错 裂纹扩展 

分 类 号：TG146[一般工业技术—材料科学与工程] O77[金属学及工艺—金属材料]