冲击速度对单晶镍层裂行为的影响规律及作用机制  

Law and mechanism of impact velocity on spalling and fracture behavior of single crystal nickel

作　　者：王路生 罗龙 刘浩 杨鑫[2] 丁军 宋鹍 路世青 黄霞 Wang Lu-Sheng;Luo Long;Liu Hao;Yang Xin;Ding Jun;Song Kun;Lu Shi-Qing;Huang Xia(College of Mechanical Engineering,Chongqing University of Technology,Chongqing 400054,China;School of Environment and Resource,Southwest University of Science and Technology,Mianyang 621000,China)

机构地区：[1]重庆理工大学机械工程学院,重庆400054 [2]西南科技大学环境与资源学院,绵阳621000

出　　处：《物理学报》2024年第16期118-129,共12页Acta Physica Sinica

基　　金：国家自然科学基金青年基金(批准号:12202081);重庆市自然科学基金面上项目(批准号:CSTB2023NSCQ-MSX0363);重庆市教委科学技术研究计划青年项目(批准号:KJQN202301117)资助的课题.

摘　　要：为了阐明冲击速度对单晶镍冲击层裂行为的影响机理,采用非平衡分子动力学方法获得了不同冲击速度下单晶镍自由面的速度、径向分布函数、原子晶体结构、位错和孔洞演化过程.结果表明单晶镍层裂行为的临界冲击速度为1.5 km/s,当冲击速度U_(p)≤1.5 km/s时,层裂机制为经典层裂损伤,而U_(p)>1.5 km/s时表现出微层裂损伤.相比经典层裂,微层裂下孔洞数量显著增加,分布更为分散,应力区域宽.分析了冲击速度对经典层裂损伤行为(U_(p)≤1.5 km/s)的影响,并获得了相应的层裂强度,当U_(p)=1.3 km/s时,发生层裂强度突变.单晶镍的层裂强度与层错、相变和位错机制共同作用.随着位错形核和发射位错数量增加,导致层裂强度先下降.当冲击速度U_(p)<1.3 km/s时,层裂损伤主要由层错作用影响;当U_(p)=1.3 km/s时,层裂强度主要受到层错与相变共同竞争作用;当冲击速度U_(p)>1.3 km/s,层裂强度主要由BCC相变机制影响,其相变机制为相变路径为FCC→BCT→BCC的马氏体相变机制.本文揭示了冲击速度对层裂损伤和断裂影响规律及作用机制,可为镍基材料在极端冲击条件下的防护应用提供理论基础.In order to reveal the influence of impact velocity(U_(p))on the spalling and fracture behavior of single crystal nickel,a non-equilibrium molecular dynamics approach is adopted to investigate the free surface velocity curve,radial distribution function,atomic crystal structures,dislocations,and void evolution process.The results show that the critical impact velocity U_(p)for spalling behavior in single crystal nickel is 1.5 km/s,and when U_(p)≤1.5 km/s the spallation mechanism is classical spallation damage and when U_(p)>1.5 km/s it behaves as micro-spallation damage.The pore number and distribution area,and stress distribution area under micro-spallation damage are much higher than those under classical spallation damage.The influence of impact velocity on the classical spalling damage behavior(U_(p)≤1.5 km/s)is analyzed and the corresponding spalling strength is obtained,indicating that an accident of spalling strength occurs when U_(p)is 1.3 km/s.The spalling strength of single crystal nickel is influenced by the combined effects of stacking faults,phase transformation,and dislocation.As the nucleation and emission of dislocations increase,the spalling strength decreases.When U_(p)<1.3 km/s,the spalling damage is mainly due to stacking faults.When U_(p)=1.3 km/s,the spalling strength is mainly affected by the competition between stacking faults and phase transformation.When U_(p)>1.3 km/s,spalling strength is predominantly influenced by the body-centered cubic(BCC)phase transformation mechanism(transformation path:FCC→BCT→BCC).This study reveals the impact velocity-dependent patterns,mechanisms,and effects on spalling damage and fracture,providing a theoretical basis for realizing the protective application of nickel-based materials under extreme impact conditions.

关 键 词：冲击速度 单晶镍 层裂 相变 分子动力学 

分 类 号：TG146.15[一般工业技术—材料科学与工程]