离子注镧对镍表面氧化膜生长机制及应力水平的影响

对纯镍及其表面离子注镧样品在900℃空气中的恒温氧化规律进行了研究.采用扫描电子显微镜(SEM)和透射电子显微镜(TEM)对NiO膜的微观形貌和结构进行测试.采用激光拉曼(Raman)谱和X射线衍射仪(XRD)对两种样品表面氧化膜的应力状态进行测量.采用二次离子质谱(SIMS)对氧化膜内元素Ni、O和La的深度分布情况进行了测量.结果表明,离子注镧显著降低了镍的恒温氧化速率,细化了表面NiO膜的晶粒尺寸,同时,将氧化膜生长的生长机制由未注镧前Ni~(2+)阳离子向外扩散转变为注镧后O~(2-)阴离子向内扩散为主.X射线衍射和激光拉曼测量均反映出注镧引起的膜内应力降低效应,并且,结合氧化膜内应力深度分布的不均匀性及膜生长过程中存在的稀土元素效应对两种应力测量结果之间存在的偏差进行了细致分析.     

Influence of Yttrium Ion-Implantation on the Growth Kinetics and Micro-Structure of NiO Oxide Film

Isothermal and cyclic oxidation behaviours of pure and yttrium-implanted nickel were studied at 1000℃ in air. Scanning electronic microscopy （SEM） and transmission electronic microscopy （TEM） were used to examine the micro-morphology and structure of oxide scales formed on the nickel substrate. It was found that Y-implantation significantly improved the anti- oxidation ability of nickel in both isothermal and cyclic oxidizing experiments. Laser Raman microscopy was also used to study the stress status of oxide scales formed on nickel with and without yttrium. The main reason for the improvement in anti-oxidation of nickel was that Y- implantation greatly reduced the growing speed and grain size of NiO. This fine-grained NiO oxide film might have better high temperature plasticity and could relieve parts of compressive stress by means of creeping, and maintained a ridge character and a relatively low internal stress level. Hence yttrium ion-implantation remarkably enhanced the adhesion of protective NiO oxide scale formed on the nickel substrate.