含空位γ—TiAl合金沿不同晶向拉伸特性研究

The effect of orientations on tensile property of single crystal γ-TiAl alloys with certain vacancy concentration

摘要:

采用分子动力学模拟方法研究了含空位缺陷的γ-TiAl合金在不同晶向下的拉伸行为。通过一系列模拟分析了空位和晶格取向对力学性能和微观缺陷演化的影响。结果表明，晶向对Ti和Al空位的临界应力有明显的影响。含Ti空位模型的屈服应力高于含Al空位模型。在单晶γ-TiAl合金的变形过程中，发现位错密度与堆叠错数具有相同的变化趋势。此外，还讨论了温度对屈服强度的影响。随着温度的升高，材料的极限应力呈非线性下降，弹性模量明显降低。温度越高，晶体向和空位缺陷对极限应力的影响越小。

Abstract:

The tensile behavior of γ-TiAl alloys with vacancy defects has been studied by molecular dynamics simulation (MD) considering different lattice orientation. A succession of simulations were performed to analyze the effect of vacancy and lattice orientation on mechanical properties and micro-defect evolution. The results indicate that the orientation has evidently impacts on critical stress with Ti and Al vacancy. The yield stress of the model with Ti vacancy is higher than containing Al vacancy model along three crystal directions. During the deformation of single crystal γ-TiAl alloys, it is found that the dislocation density has the same changeable trend as the number of stacking faults. In addition, the influence of temperature on yield strength also was discussed. When the temperature increases, the ultimate stress declines non-linearly, and elastic modulus of the material decrease obviously. The higher temperature, the less influence of crystal orientation and vacancy defect on the ultimate stress.