分子动力学模拟不同层错能单晶Ni及其合金拉伸变形行为  

Molecular Dynamics Simulation of Tensile Deformation Behavior of Monocrystalline Ni and Its Alloys with Different Stacking Fault Energies

作　　者：陈建军 丁雨田[1,2] 马元俊 高钰璧 王兴茂 Chen Jianjun;Ding Yutian;Ma Yuanjun;Gao Yubi;Wang Xingmao(School of Materials Science and Engineering,Lanzhou University of Technology,Lanzhou 730050,China;State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals,Lanzhou University of Technology,Lanzhou 730050,China;School of Mechanical Engineering,Lanzhou Petrochemical University of Vocational Technology,Lanzhou 730060,China)

机构地区：[1]兰州理工大学材料科学与工程学院,甘肃兰州730050 [2]兰州理工大学省部共建有色金属先进加工与再利用国家重点实验室,甘肃兰州730050 [3]兰州石化职业技术大学机械工程学院,甘肃兰州730060

出　　处：《稀有金属材料与工程》2023年第9期3186-3197,共12页Rare Metal Materials and Engineering

基　　金：国家重点研发计划(2017YFA0700703);甘肃省科技重大专项(145RTSA004)。

摘　　要：采用分子动力学模拟了不同尺寸模型的单晶Ni及Ni_(57)Cr_(19)Co_(19)Al_(5)合金[100]晶向拉伸变形过程,确定了具有稳定塑性流变应力的模型尺寸,进一步研究了在具有稳定塑性流变应力的相同模型下单晶Ni及其合金拉伸变形行为。结果表明,层错能较低的单晶Ni_(57)Cr_(19)Co_(19)Al_(5)合金在小尺寸模型拉伸变形时,容易形成多层孪晶结构或变形孪晶;模型的横截面边长大于30倍的晶格常数时,塑性流变阶段流变应力、相结构及位错密度随应变起伏趋于平稳。具有稳定流变应力的相同尺寸单晶Ni及其合金拉伸时,层错能越低,塑性变形时层错面的面积越大。Shockley不全位错在单晶Ni及其合金塑性变形过程中起主导作用,多层孪晶的形成伴随着位错耗尽,变形孪晶的形成与湮灭则主要由位错饥饿机制主导。The uniaxial tensile deformation of monocrystalline Ni and Ni_(57)Cr_(19)Co_(19)Al_(5) alloy models with different cross-sectional size models in the[100]orientation was simulated by molecular dynamics,and the appropriate simulation model size with stable plastic flow stress was determined.The tensile deformation behavior of monocrystalline Ni and its alloys of the same model with stable flow stress were further studied.The results show that the monocrystalline Ni_(57)Cr_(19)Co_(19)Al_(5) alloy with smaller model sizes are likely to form multi-layer twins or deformation twins during the tensile process because of low stacking fault energy.As the cross-sectional side length of model is greater than 30 times of lattice constant,the fluctuation of the flow stress,phase structures and dislocation density in the plastic flow stage tends to be stable with the variation of strain.When the monocrystalline Ni and Ni-based alloys with same model at stable flow stress stage are stretched,the lower the stacking fault energy is,the larger the area of the stacking faults plane during plastic deformation.During the tensile process of monocrystalline Ni and Ni-based alloys,Shockley partials play a leading role in the plastic deformation process.The formation of multi-layer twins is accompanied by dislocation exhaustion,while the formation and annihilation of deformation twins are mainly dominated by the dislocation starvation mechanism.

关 键 词：分子动力学模拟 单晶Ni基合金 层错能 孪晶 位错 

分 类 号：TG111.2[金属学及工艺—物理冶金] TG146.15[金属学及工艺—金属学]