显微组织演变
( 1. 西安交通大学 金属材料强度国家重点实验室，
西安 710049；
2. 西安建筑科技大学 材料科学与工程学院， 西安 710055)
摘 要: 在研究Ti， C， A1摩尔比为2∶1∶1的混合粉末自蔓延高温合成Ti↓2AlC过程中的组织演变中，将在试样中蔓延的燃烧波强制淬熄。 用扫描电镜观察了淬熄试样中的显微组织演变， 测定了其燃烧温度， 并用X射线衍射检测了燃烧合成产物的相组成。 结果表明： 合成反应以Al的熔化为先导； 反应过程可用溶解—析出—熔化—结晶机制描述；该反应具有不完全性， 可能是由于实验中使用了较粗的钛粉和铝粉所致。
关键字: Ti2AlC；可加工陶瓷； 自蔓延高温合成； 组织演变
temperature synthesis of Ti2AlC machinable ceramics
（ 1. State Key Laboratory for Mechanical Behavior of Materials，Xi′an Jiaotong University，
Xi′an 710049， China；
2. School of Materials Science and Engineering，
Xi′an University of Architecture and Technology， Xi′an 710055， China）
Abstract: In the study of microstructural evolution during self-propagating high-temperature synthesis of Ti2AlC machinable ceramics from Ti-Al-C powders, a propagating combustion wave in the sample was quenched, and the microstructural evolution was observed with scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The combustion temperature was measured, and the phase constituent of the synthesized product was inspected by X-ray diffraction (XRD). The results show that the combustion reaction is preceded by melting of the Al particle, and it proceeds in a dissolving-precipitating-melting-crystallizing mechanism. In addition, the reaction is incomplete, this is because the coarser Ti and Al powders are used in the experiment.
Key words: Ti2AlC； machinable ceramics； self-propagating high-temperature synthesis； microstructural evolution
