Y2O3掺杂BaZrO3显微组织演变及与钛熔体相容性

Microstructure evolution of Y_2O_3 doped BaZrO_3 and its interface reaction with titanium melt

以BaCO_3、ZrO_2和Y_2O_3为原料的6种配比混合料在1200℃经固相合成Y_2O_3掺杂BaZrO_3粉体,并经冷等静压成型后在1750℃烧结成圆片。利用X射线衍射仪(XRD)和扫描电子显微镜(SEM)结合能谱分析(EDS)分析不同Y_2O_3掺杂量对BaZrO_3粉体组成及其对BaZrO_3圆片的显微组织结构和烧结性能的影响。结果表明:Y_2O_3掺杂BaZrO_3主要由BaZrO_3和Ba2YZr O6构成;随着Y_2O_3掺杂量的增加,Ba2YZr O6含量逐渐增加,并出现团聚现象;同时,BaZrO_3晶粒生长受到抑制,导致圆片表面疏松多孔,致密度降低。当原料摩尔比n(BaCO_3):n(ZrO_2):n(Y_2O_3)=0.48:0.47:0.1时,所获圆片相对密度达到97.1%。使用该配比粉料制备坩埚感应熔炼Ti Ni合金后,合金与坩埚无界面反应层存在,也未见明显坩锅组成元素向合金扩散现象,说明Y_2O_3掺杂BaZrO_3是一种非常有潜力的钛合金熔炼制备用耐火材料。

Six ratios of Y2O3 doped BaZrO3 powder were prepared from BaCO3, ZrO2 and Y2O3 as raw materials by solid reaction method at 1200 ℃. Then, the pellets were fabricated by cold isostatic pressing and sintered at 1750 ℃. The effect Y2O3 on the constituents of BaZrO3 powder and microstructure evolution of BaZrO3 pellets was studied by using the X-ray diffraction (XRD) and scanning electron microscopy (SEM) combined with EDS. The results show that the Y2O3 doped BaZrO3 mainly consists of two phases, i. e., BaZrO3 and Ba2YZrO6. The content of Ba2YZrO6 increases gradually and the phenomenon of aggregation appears as the amount of Y2O3 increasing. At the same time, the growth of BaZrO3 grains are restrained, the grain boundaries of BaZrO3 and Ba2YZrO6 transform from regular polyhedron boundary to irregular amorphous grain boundary, which make the surface of the pellets porous and lower dense. When the mole ratio of BaCO3, ZrO2 and Y2O3 is about 0.48:0.47:0.1, the relative density of pellets reaches to 97.1%. This proportion of powder was prepared into crucible and utilized to melt TiNi alloys using vacuum induction. There is no obvious interaction layer and elements diffusion between the crucible and the melt, which may imply that the Y-doped BaZrO3 refractory is a promising candidate for melting titanium alloys.