Research on a New Synthesis Technology of La-Mg-Ni System Alloys and Microstructure of La0.67Mg0.33Ni3.0 Alloys

摘要:

以含La、Mg、Ni元素的化学试剂为原料，先制得三元复合金属氧化物前驱体；再以优化后的实验参数，进行基于共沉淀及还原扩散法联用工艺制备La0.67Mg0.33Ni3.0合金及其微观结构的研究，并验证新型合成工艺的可行性。结果表明：以共沉淀和还原扩散法制得的合金均为多相结构，其组织和成分趋于均匀化，晶格畸变小；并且合金还原过程比较彻底，合金中含氧量极少,取得了预期的效果；La-Mg-Ni系合金新型合成工艺可行，但还需对该工艺进行再优化

Abstract:

The isothermal oxidation behavior of a new Ni-Cr-W base superalloy Ni-20Cr-18W at 1100 oC has been investigated by analytical electron microscopy, scanning electron microscope coupled with energy dispersive spectrum and X-ray diffraction. Oxidation kinetics was evaluated from measurements of mass change, metal loss and internal penetration. Initially, the mixtural oxide scale is composed of hexagonal Cr2O3, cubic NiO and spinel-type (Ni，Mn，Cr)3O4 isomorphous with M3O4 at the initial stage of oxidation. After long-term oxidation, the oxide scale turns from mono-layer to double-layer. There is a consecutive Cr2O3 scale at inner adherent layer, and a compact NiO scale at outer layer which can restrain the inner Cr2O3 volatilization. At the same time, the oxidation void has formed between the oxide scale and interface of the alloy (scale/metal interface), and the inner oxidation of Al element happens at this place