摘要
用分子动力学方法研究面心立方SiC(β-SiC)、C元素置换掺杂β-SiC单晶块体体系[001]向拉伸变形行为,对体系的拉伸断裂微观机理和5×108/s,1×109/s,1×1010/s三种应变速率下的力学行为进行分析.发现当拉伸应变量达到某个临界值后,Si-C sp3,C-C sp3键会分别向Si-C sp2和C-C sp2弱键转化.形成一定量sp2键后,β-SiC内部出现孔洞并发生断裂.由于C-C sp3键比Si-C sp3键更易向sp2弱键转化,导致C元素掺杂会降低SiC的强度、弹性模量和拉伸断裂应变.此外还发现此三种应变速率不影响β-SiC的杨氏模量,但影响其拉伸强度.
Tension simulations of [001]monocrystalline face-centered cubic SiC（β-SiC） and C-doped β-SiC bulks are performed with molecular dynamics method to investigate intrinsic deformation mechanisms and mechanical behaviors of β-SiC under strain rates of 5×108/s,1×109/s,1×1010 /s.It is found that Si-C sp3 and C-C sp3 bonds respectively transform to Si-C sp2 and C-C sp2 bonds as soon as the strains reach certain critical values.As certain amounts of sp2 bonds are formed,instable fractures emerge in β-SiC.Since C-C sp2 bonds are formed earlier than Si-C sp2 bonds,the doping of C elements leads to the decrease of strength,Young’s modulus and tension fracture strain of β-SiC.In addition,it is found that the strain rates have effects on tensile-strength,but not on Young’s modulus.
出处
《计算物理》
EI
CSCD
北大核心
2010年第6期898-904,共7页
Chinese Journal of Computational Physics
基金
教育部留学回国人员科研启动基金(2006-331)
江苏大学优秀学术青年骨干培养对象基金(1211110001)资助项目
关键词
SIC
力学行为
化学键
分子动力学
SiC
mechanical behavior
chemical bonds
molecular dynamics
