Zr-Cu薄膜生长及力学性能的分子动力学模拟

Molecular dynamic simulations of the growth and mechanical properties of Zr—Cu films

  • 摘要: 根据磁控溅射实验条件, 采用分子动力学方法, 在Si(100)面上模拟沉积了三种ZrxCu100-x(x=50, 70和90)合金薄膜.通过计算径向分布函数(RDF)及X射线衍射(XRD)分析了沉积薄膜的形貌结构, 并探讨了玻璃形成能力和五重局部对称性之间的关系.最后研究了沉积薄膜的力学性能, 及薄膜厚度对拉伸过程的影响.研究结果表明: Zr-Cu合金玻璃形成能力与五重局部对称性之间存在一定的相关性, 沉积玻璃薄膜比晶体薄膜表现出更好的延展性, 其中Zr50Cu50沉积玻璃薄膜比近共晶成分玻璃薄膜(Zr70Cu30)具有更大的拉伸强度; 沉积薄膜存在一定的尺寸效应, 薄膜相对厚度越小, 其拉伸强度越大.

     

    Abstract: The binary Zr-Cu system is a paradigm for studying the atomistic structure-property relationships and glass transition due to its outstanding glass formation ability (GFA). Metallic glass (MG) thin films are mainly prepared using magnetron sputtering deposition methods. The outstanding mechanical properties of these MG thin films have gained the attention of the industry. In this study, molecular dynamic (MD) simulations were employed to investigate the growth of ZrxCu100-x(x=50, 70, and 90), with initial conditions similar to the experimental operating ones. The deposition process of the Zr-Cu system was performed on the Si (100) substrate. The simulated radial distribution functions (RDF) and X-ray diffraction (XRD) were adopted to analyze the phase of Zr-Cu films. Additionally, the correlation between GFA and five-fold local symmetry (FFLS) was discussed in depth. The mechanical properties of the deposited films and the effect of film thickness on the tensile process were also analyzed. The results show that the structure is composition-dependent. Both Zr50Cu50 and Zr70Cu30-deposited films exhibited amorphous properties with strong short range orders, whereas Zr90Cu10 -deposited film showed a perfect crystal characteristic. The positive correlation exists between GFA and degree of FFLS in binary Zr-Cu systems. Zr90Cu10 -deposited film has a Young's modulus of 100 GPa, which is larger than that of the other two deposited films. Deposited Zr-Cu MG films exhibited better ductility than crystalline ones. Herein, the failure strain of Zr-Cu MG films exceeded 40%. The correlation existed between GFA and mechanical strength. Deposited films with higher GFAs had greater strength at the same box size. Moreover, the Zr50Cu50 -deposited glass film had greater ultimate tensile strength than the near-eutectic glass film (Zr70Cu30). This study also shows that the deposited film exhibited a certain size effect. The size effect was detected, and when the thickness of the film was smaller, the tensile strength was greater. This study provides new ideas for the preparation of MG films with perfect mechanical properties.

     

/

返回文章
返回