自生Ti2AlC/TiAl复合材料的组织及反应过程

Microstructure and Reaction Process of In-situ Ti2AlC/TiAl Composite

摘要:

采用自蔓延燃烧合成及真空电弧熔炼的方法，以碳纤维（Cf）、钛粉及铝粉为原料，合成了Ti2AlC/TiAl复合材料。通过X射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)分析了复合材料的物相组成和微观结构，讨论了原位合成Ti2AlC的反应和二次Ti2AlC的析出过程。结果表明，复合材料铸锭由Ti2AlC、TiAl和Ti3Al 3相组成，基体由α2(Ti3Al)+γ(TiAl)片层和γ(TiAl)等轴晶粒构成，原位自生的Ti2AlC分布均匀，呈短纤维状或颗粒状。1200 ℃均匀化热处理促使Ti3Al分解为TiAl和Ti2AlC，导致Ti2AlC粗化，同时基体表面析出细小的二次Ti2AlC颗粒。

Abstract:

Ti2AlC/TiAl composite was prepared with self-propagating high-temperature synthesis (SHS) followed by vacuum arc melting using Ti, Al powers and short carbon fibers as raw materials. Precipitated phases and formed microstructures of Ti2AlC/TiAl composite were investigated by means of X-ray diffraction, scanning electron microscope and transmission electron microscopy, and the reaction process was also discussed. Results show the microstructure of as-cast Ti2AlC/TiAl composite is composed of Ti2AlC, TiAl and Ti3Al phases, the matrix are mainly of α2(Ti3Al)+γ(TiAl) phases with lamellar structure and γ(TiAl) phase with equiaxed structure, and the precipitated in-situ Ti2AlC short fibers or particles dispersively distribute in the matrix. Ti3Al phase is decomposed to TiAl and Ti2AlC particles after annealed at 1200 °C for 4 h, and the Ti2AlC short fibers are enlarged and secondary Ti2AlC is precipitated after the annealing treatment.