Al含量对单晶TiAl合金力学性能的影响（英文）

Effects of Al Content on the Mechanical Properties of Single Crystal TiAl Alloy

通过改变TiAl中Al的含量,用分子动力学方法研究了Al含量对含有裂纹的单晶TiAl试件性能及裂纹扩展的影响,分析了不同Al含量下的应力-应变曲线,缺陷的演化过程。模拟结果表明:Al含量不同,材料的弹性模量和强度也不同。Al含量低于45 at%时,由于层错和位错的产生以及位错反应和运动产生的空位和空位的迁移提高了试件的塑性使得试件表现出良好的塑性,而大于该含量时,试件呈明显的脆性;Al含量较低时,裂纹以塑性变形的方式扩展,Al含量较高时,裂纹以脆性方式断裂。即Al含量会影响材料的性能;随着Al含量降低,试件的塑性增强,此外,Al含量对裂纹的扩展机制也有很大影响。

The effects of Al content on the mechanical properties and the crack propagation mechanism of single crystal TiAl was discussed using molecular dynamics simulation. The stress-strain curves and evolution process of the defects were obtained under different Al contents. The results show that the Al content would affect the elastic modulus and the strength of the TiAl alloy. Defects such as stacking faults, dislocations and vacancies and their migrations result in better plasticity of TiAl when the Al content is below 45 at%. However, the specimen exhibits obvious brittleness with the Al content greater than 45 at%. Furthermore, the plasticity deformation dominates the main mode under the low Al content, while the crack fracture presents brittleness when the Al content is high. Therefore, Al contents would affect the mechanical proprieties of TiAl alloy, i.e. the plasticity of TiAl would increase with the decreasing Al content. In addition, the mechanism of crack propagation would vary with the change of Al content.