摘要
采用多靶磁控溅射法制备了一系列具有不同TiB2调制层厚度的TiN/TiB2纳米多层膜.利用x射线衍射仪、高分辨电子显微镜和微力学探针研究了TiB2层厚变化对多层膜生长结构和力学性能的影响.结果表明,在fcc-TiN层(111)生长面的模板作用下,原为非晶态的TiB2层在厚度小于2·9nm时形成hcp晶体态,并与fcc-TiN形成共格外延生长;其界面共格关系为{111}TiN//{0001}TiB2,〈110〉TiN//〈1120〉TiB2.由于共格界面存在晶格失配度,多层膜中形成拉、压交变的应力场,导致多层膜产生硬度和弹性模量升高的超硬效应,最高硬度和弹性模量分别达到46·9GPa和465GPa.继续增加TiB2层的厚度,TiB2形成非晶态并破坏了与TiN层的共格外延生长,多层膜形成非晶TiN层和非晶TiB2层交替的调制结构,其硬度和弹性模量相应降低.
TiN/TiB2 nanomuflialyers with different TiB2 layer thickness were prepared using multi-target magnetron sputtering method. The effects of TiB2 layer thickness on the growth structure and mechanical properties of nanomultialyers were studied by X-ray diffraction, high-resolution transmission electron microscopy and nanoindentation respectively. The results reveal that the normally amorphous TiB2 layers crystallize in close-packed hexagonal structure when its thickness is less than 2.9 nm due to the template effect of cubic TiN layers. Coherent growth is found between TiN and TiB2 layers with the orientation relationship of { 111} TiN//{ 0001 } TiB2 , （110 ）TiN//（ 1120）TiB2 . Because of the lattice misfit, an alternating tensile/compressive stress field develops in the nanomultilayers, which leads to the anomalous enhancement of hardness and elastic modulus. Maximum hardness and elastic modulus of 46.9 and 465GPa are obtained at TiB2 layer thickness of 0.6nm. With increasing TiB2 layer thickness, amorphous TiB2 forms and blocks the coherent growth of the multilayers. Consequently, the hardness and elastic modulus of the films decrease gradually.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2005年第10期4846-4851,共6页
Acta Physica Sinica
基金
上海市纳米技术专项基金(批准号:No.0352nm084)资助的课题.~~
