切削深度对单晶γ-TiAl合金力学性能的影响

Effect of cutting depth on mechanical properties of single crystal γ-TiAl alloy

摘要:

在本文，通过分子动力学模拟方法建立了单晶γ-TiAl合金的纳米切削模型和拉伸模型，其主要分析不同的切削深度对工件拉伸性能的影响。一方面，详细的研究了晶格转变和微观缺陷演化之间的关系；另一方面，系统的探讨了不同的切削深度对应力-应变曲线、位错形核位置和工件断口位置的影响。研究结果表明：在纳米切削阶段，晶格转变的数量会随着切削深度的增加而增多并且与微观缺陷演化具有一致性。在一定的切削深度范围内工件的屈服应力和弹性模量会相应的提高。另外，切削深度对工件的位错形核位置和断口位置有较大影响，经过加工的工件位错形核于工件的亚表面，而未经过加工的位错形核于工件的边界处，工件的断口位置随着切削深度的增加越靠近拉伸端。

Abstract:

In this paper, the nano-cutting and tensile model of monocrystalline γ-TiAl alloy was established by Large scale molecular dynamics simulations method. The objective is to analyze the effect of different cutting depths on tensile process of workpiece. For one thing, the relationship between lattice transformation and micro-defect evolution is studied in detail. For another, the influences of different cutting depths on stress-strain curve, the nucleation of dislocation and position of fracture surface are discussed. The research results show that amount of lattice transition rises with increases of cutting depth and consistents with micro-defect evolution during nano-cutting. Within a certain range of cutting depth, the yield stress and elastic modulus of workpiece are improved correspondingly. In addition, cutting depths have great influence on the position of dislocation nucleation and fracture surface of workpiece during tensile process. The dislocation of machined workpiece is nucleated at subsurface, while dislocation of unmachined workpiece is nucleated at edge of workpiece. The port position of workpiece is closer to drawing end with cutting depth increases.