Ni－La_2O_3复合镀层中的质点弥散与组态研究

用金相、电子探针（ＥＰＭＡ）、透射电镜（ＴＥＭ）及高分辨电子显微镜（ＨＲＥＭ）对Ｎｉ－Ｌａ２Ｏ３复合电镀层的表面形貌及ＬａＯ３质点在镀层中的存在情况进行了研究．发现随着镀液中Ｌａ２Ｏ３颗粒含量增加，复合镀层中Ｌａ２Ｏ３的弥散量增多，镀层晶粒细化．Ｌａ２Ｏ３质点以两种组织状态均匀分布于镍层中：其一为纳米级晶体（绝大多数＜５０ｎｍ）的弥散状态；另一种为微米级（～１μｍ）的“聚合体”状态，是由更微小的纳米晶体（～１０ｎｍ）所组成，由于Ｎｉ－Ｌａ２Ｏ３复合镀层用作扩散渗铝制备Ｌａ２Ｏ３氧化物改性的铝化物涂层的基底层，文中还就复合涂层的Ｌａ２Ｏ３质点弥散与组态对改性的铝化物涂层的显微结构及其氧化行为的影响作了进一步探讨．

DISPERSION AND MORPHOLOGY OF La_2O_3 PARTICLES IN Ni-La_2O_3 ELECTRODEPOSITED COMPOSITE FILM

The morphology and microstructure of Ni-La2O3 codeposited films were studied by means of metallograph, electron probe microanalyzer (EPMA) ,transmission electron microscope (TEM) and high resolutionelf3ctroli microscope (HREM). It was found that the amount of La2O3 in the Ni codeposited film lucreasedwith increasing amount of La2O3 particles in the plating bath, and that the presence of La2O3 particlesin the films resulted in the reduction of the nickel grain size. Two kinds of morphologies of codepositedLa2O3 inclusions were observed in the nickel composite film: one consisted of the dispersed nanometer-sizeparticles, most of which were less than 50 nm in diameter; the other was micrometer-size " agglomeratedclusters" which were comprised of nanocrystallites less than 10nm. Since the Ni-La2O3 codeposited filmon Ni-base superalloy was prepared as the matrix layer for diffusion aluminizing to obtain La2O3-modifiedaluminide coating, the effect of the La2O3 inclusions in the Ni-La2O3 films on the microstructure of thealuminide coating and its oxidation behavior was also investigated.