ZrAlN薄膜的硬度和韧性与相结构的关系

The relationship of hardness and toughness with phase of magnetron sputtering ZrAlN films

Al在ZrN薄膜中的存在形式与Al含量密切相关,由此导致ZrAlN薄膜的韧性改变。本文发现了一定成分的ZrAlN薄膜同时具备高硬度和高韧性的现象。采用磁控溅射技术在钛合金和单晶Si上沉积不同Al含量的ZrAlN薄膜,测试了硬度(H)、弹性模量(E)和断裂韧性(KIC),表征了微观组织、相结构,阐明了性能变化机理。采用纳米压入仪测试H和E;压入法及小能量多冲法评价了KIC;采用场发射扫描电镜(FESEM)观察截面形貌,X射线衍射(XRD)分析物相结构。实验发现:当向Zr N薄膜(18.9 GPa)中加入5at%,23at%,47at%和63at%Al后,对应硬度分别是24.5,40.1,17.1和19.1 GPa;对应断裂韧性分别是1.47,3.17,1.13和1.58 MPa·m-0.5,即23at%Al的薄膜同时具备最高的硬度(40.1 GPa)和最高的韧性(3.17 MPa·m-0.5)。XRD表明,5at%和23at%Al固溶到Zr N晶粒中,形成Na Cl型面心立方(FCC)结构,而47at%和63at%Al则形成纤锌矿密排六方(HCP)Al N第二相。采用两种方法定量地评价了薄膜的韧性。

ZrAlN thin films containing variable amounts of aluminum, namely 5, 23, 47 and 63at%, were deposited onto TC6 and Si wafers by magnetron sputtering in an argon/nitrogen gas mixture. The ZrAIN coatings were characterized with Field Emission Gun Scanning Electron Microscopy （FESEM） and X-ray Diffraction （XRD）. The plastic deformation of films was analyzed from loading/unloading curves measured by nano-indentation method. The fracture toughness of films were determined by Vicker Indenter Load and Low-Load Impact method. The results show that ZrA1N films possess hardness values of 24.5, 40.1, 17.1 and 19.1 GPa, and fracture toughness values of 1.47, 3.17, 1.13 and 1.58 MPa·m^-0.5, respectively. 23at%ZrAlN possesses highest hardness and toughness. XRD indicates that 5at% and 23at%Al dissolved within ZrN grains forms the NaC1 type face-centered cubic （FCC） structures whereas 47at% and 63at%Al forms wurtzite A1N second phase.