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采用内聚力单元模拟镍基单晶合金中基体与夹杂之间的界面,对镍基单晶合金中空穴绕夹杂形核及扩张的过程进行了初步的分析。夹杂-基体界面的粘结强度不同,空穴的相对体积分数增长速度存在较大差异。粘结强度越小,空穴越容易形核,空穴扩张的速率越大;粘结强度越大,空穴越难于形核,空穴扩张的速率越小。应力三维度是空穴形核及扩张的主要驱动力,应力三维度越高,空穴形核及扩张的速率越大。应力三维度不同时,基体-夹杂界面开裂的初始位置及裂纹扩展的方式不同。在高应力三维度下空穴的演化由低应力三维度时的形状改变为主变为体积膨胀为主。Lode参数对空穴的形核过程及空穴形成后的扩张有着显著的影响。晶体取向对空穴的形核过程有着显著的影响,不同取向时基体-夹杂界面开裂的初始位置及裂纹扩展的方式不同。晶体取向对空穴的扩张有着显著的影响。在考虑镍基单晶合金的晶体取向相关性时,必须同时考虑Schmid系数、弹性模量和开动的滑移系。
The cohesion element was used to simulate the interface between the matrix and inclusions in the nickel-based single crystal alloy. The nucleation and expansion of the holes around the nickel-based single crystal alloy were analyzed preliminarily. Inclusion - matrix interface bonding strength is different, the relative growth of the volume fraction of holes there is a big difference. The smaller the bond strength, the easier nucleation of holes, the greater the rate of hole expansion; the larger the bond strength, the more difficult the nucleation of holes, and the slower the rate of hole expansion. Three-dimensional stress is the main driving force for the nucleation and expansion of cavities. The higher the three-dimensional stress, the greater the rate of hole nucleation and expansion. When the three dimensional stress is different, the initial crack initiation and crack propagation in the matrix-inclusion interface are different. In the three-dimensional high stress, the evolution of cavities is dominated by the change in shape from low-stress three-dimensional to main-volume expansion. The Lode parameter has a significant effect on the nucleation of holes and the expansion after the formation of holes. The crystal orientation has a significant influence on the nucleation process of holes, and the initial locations of crack initiation and crack propagation at different orientations are different. Crystal orientation has a significant effect on cavity expansion. In considering the crystal orientation dependence of a nickel-based single crystal alloy, it is necessary to consider both the Schmid coefficient, the elastic modulus, and the slipping system that starts.