等轴应变作用下Cu,Al薄膜的取向择优生长

PREFERENTIAL GROWTH OF COPPER AND ALUMINUM FILMS UNDER BIAXIAL STRAIN

用分子动力学方法模拟了Cu双晶和Al双晶薄膜的<111>生长,模拟时假定在薄膜平面内保持恒定的等轴双向应变, 薄膜中两晶粒的能量计算表明:不同晶粒的能量存在差异,能量较低的晶粒在沉积中择优生长,逐渐取代能量较高的晶粒, Cu膜择优生长速率显著高于Al膜;两种薄膜择优生长的机制完全不同,Cu膜中处于不利位向的晶粒通过孪晶过渡转变为择优取向, 转变完成、晶界湮灭后薄膜中残留的缺陷为位错;而Al膜则是通过无序结构重结晶实现上述转变,转变完成、晶界湮灭后薄膜中残留的缺陷为间隙原子.文中对上述择优生长驱动力的来源、以及在纳米多晶中的重要性进行了讨论.

Molecular dynamics simulations of （111） growth of copper and aluminum bicrystal films under biaxial strain have been carried out. The calculation of the energies show that exists a difference between different grains and the grain with lower energy gradually replaces one with higher energy. The process for copper film is much faster than that for aluminum film, indicating their mechanisms different. In copper film, the transition of grains from disfavored to favored orientations is through twinning and the defect left after boundary annihilation is a semi-dislocation-loop, while in aluminum film, the transition is through a disordered structure and the defect left is a cluster of interstitial atoms. The driving force for the preferential growth under biaxial strain and its significance to nanocrystalline materials are discussed.