Li Wei-bing, Li Kang, Fan Kang-qi, Zhang Da-xing, Wang Wei-dong
ZNDY of Ministerial Key Laboratory, Nanjing University of Science and Technology, Nanjing, 210094, People's Republic of China.
McCormick School of Engineering and Applied Science, Northwestern University, Evanston, IL, 60208, USA.
Nanoscale Res Lett. 2018 Apr 24;13(1):118. doi: 10.1186/s11671-018-2526-1.
Atomistic simulations are capable of providing insights into physical mechanisms responsible for mechanical properties of the transition metal of Tantalum (Ta). By using molecular dynamics (MD) method, temperature and pressure dependences of the elastic properties of Ta single crystals are investigated through <100> tensile loading. First of all, a comparative study between two types of embedded-atom method (EAM) potentials is made in term of the elastic properties of Ta single crystals. The results show that Ravelo-EAM (Physical Review B, 2013, 88: 134101) potential behaves well at different hydrostatic pressures. Then, the MD simulation results based on the Ravelo-EAM potential show that Ta will experience a body-centered-cubic (BCC) to face-centered-cubic (FCC) phase transition before fracture under <100> tensile loading at 1 K temperature, and model size and strain rate have no obvious effects on tensile behaviors of Ta. Next, from the simulation results at the system temperature from 1 to 1500 K, it can be derived that the elastic modulus of E linearly decrease with the increasing temperature, while the yielding stress decrease with conforming a quadratic polynomial formula. Finally, the pressure dependence of the elastic properties is performed from 0 to 140 GPa and the observations show that the elastic modulus increases with the increasing pressure overall.
原子模拟能够深入了解钽（Ta）这种过渡金属机械性能背后的物理机制。通过使用分子动力学（MD）方法，通过<100>拉伸加载研究了Ta单晶弹性性能的温度和压力依赖性。首先，根据Ta单晶的弹性性能对两种类型的嵌入原子法（EAM）势进行了比较研究。结果表明，Ravelo-EAM（《物理评论B》，2013年，88: 134101）势在不同静水压力下表现良好。然后，基于Ravelo-EAM势的MD模拟结果表明，在1 K温度下<100>拉伸加载时，Ta在断裂前会经历体心立方（BCC）到面心立方（FCC）的相变，且模型尺寸和应变速率对Ta的拉伸行为没有明显影响。接下来，从1到1500 K系统温度下的模拟结果可以得出，弹性模量E随温度升高呈线性下降，而屈服应力随二次多项式公式下降。最后，在0至140 GPa范围内进行了弹性性能的压力依赖性研究，结果表明弹性模量总体上随压力升高而增加。
