采用感应熔炼气体雾化法制备了TiAl预合金粉末. 粉末粒度主要分布在100-250 μm, 呈正态分布, 粉末平均粒度为120.7 μm. TiAl预合金粉末的相组成与粒度分布有关, γ相所占比例越高, 预合金粉末粒度越大. 小粒度的预合金粉末主要由α2相组成; 预合金粉末在温度高于500℃时效处理, 发生α2→γ转变. TiAl预合金粉末相组成不同会产生后续热等静压组织局部粗化现象. XPS结果表明TiAl预合金粉末颗粒表面形成Al2O3和TiO2薄膜.
TiAl pre–alloyed powder (nominal composition Ti–47Al–2Cr–2Nb–0.2W–0.15B, atomic fraction, %) was produced by electrode induction melting gas atomization (EIGA) technique. The average diameter is 120.7 μm, and the distribution of the powder diameter follows Gaussian distribution. The phase constitution is a function of particle diameter. The amount of the γ phase increases with powder diameter increasing, the finest powder consists of predominantly α2 phase. The α2 phase in the powder was transformed into γ phase after annealing at temperatures higher than 500 ℃. Local coarsening was observed in the microstructure of TiAl compact duo to the microsegregation of elements in the powder. The XPS result indicated that the outer layer of the TiAl pre–alloyed particle consists of a thin layer of Al2O3 and TiO2.
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