机械球磨与不同温度烧结下的TiAl合金研究

Investigation of TiAl-based alloys prepared by the mechanical milling method and sintered at different temperatures

文章采用测密度、硬度、金相、XRD及能谱分析的方法，研究了在不同温度下烧结后试样的显微结构。结果表明，Ti-Al（xAl=44．7％）粉末的扩散反应随机械球磨时间的延长而加快，且在低温扩散保温下转变为金属间化合物，经过45h球磨后并保温转变为γ-TiAl相和一部分α-Ti3Al；试样在700℃烧结后的显微组织呈层片状晶粒，晶粒边界不清晰；在1250℃下晶化，晶粒平均尺寸在0．3～0．6μm。

TiAl-based alloys were fabricated by the mechanical milling method, and microstructure of the samples sintered at different temperatures were investigated. Measurement and analysis of density, rigidity, metallography, XRD and EDS were carried out. The results show that mechanical milling could accelerate the diffusion reaction between Ti and Al, and that the Ti-Al（xAl=44. 7%） composite powders could be transformed into TiAl compounds. Ti-Al（xAl=44. 7%） powders have completely dissolved into F-TiAl plase after 45 h by high-energy milling in a planetary ball milling system and heat preservation although they part dissolved into α-Ti3Al at 700 ℃. The microstructure of the sample sintered at 700 ℃appears in the form of lamellar grains. The lamella size is more than 100μm and the grain boundary is not distinct. Crystallizing at 1 250 ℃, the grain has an average size from 0. 3 to 0.6μm.