多层膜晶界和膜界间竞比变形及其对硬度测量的影响

EFFECT OF COMPETITIVE DEFORMATION BETWEEN GRAIN BOUNDARY AND FILM INTERFACE ON HARDNESS MEASUREMENTS OF MULTILAYER FILMS

使用磁控溅射法制备了不同调制波长的Ni/Al多层膜,利用X射线衍射(XRD)和高分辨电子显微术(HRTEM)对薄膜进行了微结构表征,采用连续刚度法(CSM)研究了不同压入深度下多层膜的硬度．结果表明,随调制波长减小,薄膜呈纳米晶结构特征且存在超硬效应．调制波长L大于30 nm时,纳米压入硬度随压入深度的增加而升高;L小于30 nm时,最大压入深度的硬度测量值反而最小．同时发现压入深度较小时硬度相对大小对调制波长不敏感．结合微结构表征,从晶界和膜界的竞比变形角度进行了分析讨论．

Ni/Al mutlialyer films with different modulated periods （L） were prepared using multi-target magnetron sputtering method. The microstructure of multilayers was studied by XRD and HRTEM. The continuous stiffness mode （CSM） was employed to measure the effect of indentation depth on the determination of hardness of thin films by means of nanoindentation. The results reveal that the film was strengthened with increasing L, and the superhardness phenomenon was observed for Ni/Al multilayers. For the film with L more than 30 nm, depth--dependent hardness increased with enhanced indentation depth. However, the hardness at the largest indentation depth showed the lowest value for the Ni/Al film with L less than 30 nm. This tendency indicates the depth-sensing hardness for multilayer at nanometer scale, which was analyzed by a competitive effect between film interface and grain boundary.