【摘要】 研究了亚稳相立方AlN(c-AlN)在AlN/VN纳米多层膜中的形成条件以及c-AlN对纳米多层膜力学性能的影响。一系列不同调制周期的AlN/VN多层膜采用反应磁控溅射法制备,多层膜的微结构采用小角度X射线衍射和高分辨电子显微镜表征,利用微力学探针测量了多层膜的力学性能。结果表明:亚稳的c-AlN因VN的"模板"作用生成于小调制周期的纳米多层膜中,并与VN形成共格外延生长的超晶格柱状晶,从而使多层膜产生硬度和弹性模量升高的超硬效应。随调制周期的增大,c-AlN转变为稳定的六方结构(h-AlN),使多层膜形成纳米晶的"砖墙"型结构。此时多层膜的硬度和弹性模量与混合法则所得值相当。AlN/VN纳米多层膜在小调制周期下产生的超硬效应与c-AlN形成带来的性质变化以及c-AlN与VN形成共格结构所产生的界面交变应变场有关。更多还原

【Abstract】 The growth condition of mestable cubic AlN(c-AlN) in AlN/VN nanomultilayers and its effect on the mechanical properties of multilayers are investigated. A series of AlN/VN multilayers with different modulation periods are prepared by reactive magnetron sputtering technique. The microstructure and mechanical properties of multilayers are characterized by low-angle X-ray diffraction, high-resolution transmission electron microscopy and a nanoindentor. The results show that AlN exists as mestable cubic phase (c-AlN) at small modulation period due to the "template effect", and formed superlattice columnar srystal with VN through coherent epitaxial growth. Correspondingly, nanomultilayers show the superhardness effect with the enhancement of hardness and elastic modulus. With the increase of modulation period, c-AlN transformed to stable hexagonal structure (h-AlN) and multilayers form "brick-wall" structure with nanometer grains. The hardness and elastic modulus of multilayers are close to the value calculated from rule of mixture at large modulation period. The change of properties with the formation of c-AlN and alternative strain field resulted from coherent growth of c-AlN and VN appear to be one likely reason for the superhardness effect of AlN/VN nanomultilayers.更多还原