含空洞镍基单晶高温合金力学性能的分子动力学研究

Molecular Dynamics Study on Mechanical Properties of Nickel-based Single Crystal Superalloys Containing Voids

镍基单晶高温合金因其优异的性能在航空航天方面应用广泛,但是在制造过程中,不可避免有空洞缺陷的产生,从而影响合金力学性能。通过分子动力学模拟研究温度、应变速率和空洞形状对镍基单晶高温合金拉伸力学性能和位错演化的影响。结果表明:温度和应变速率影响材料力学性能,温度增加,杨氏模量减小,屈服强度减小,材料强度降低;应变速率增加,材料的杨氏模量不变,屈服强度增大。此外,空洞的存在降低了材料的强度和杨氏模量。不同形状空洞对杨氏模量影响相同,对材料强度的影响不同。菱形空洞模型由于存在锐角,位错更容易聚集,屈服强度更小,在拉伸过程中更容易断裂变形。

Nickel-based single crystal superalloys have been widely used in aerospace due to their superior properties,but there are inevitable void defects in the manufacturing process,which affect the mechanical properties of the alloy.The effects of temperature,strain rate and void shape on the tensile mechanical properties and dislocation evolution of nickel-based single crystal superalloy have been studied by molecular dynamics simulation.Results show that temperature and strain rate affect the mechanical properties of materials.With the increase of temperature,Young’s modulus,yield strength and material strength are all decreased;With the increase of strain rate,the young’s modulus of the material remains unchanged and the yield strength increases.In addition,the presence of voids reduces the strength and Young’s modulus of the material.Young’s modulus of models with different shapes of voids is the same,while strength of those is different.Due to the acute angle of the diamond-shaped void,the dislocations are more likely to aggregate,the yield strength is smaller,and it is more likely to be broken during the stretching process.