TiC-Al金属陶瓷自蔓延高温合成中的显微组织转变

用燃烧波淬熄法研究了TiC-Al金属陶瓷自蔓延高温合成中显微组织的转变,淬熄试样中保留了未反应区、反应区及反应完成区.用扫描电子显微镜观察了燃烧反应中的显微组织转变过程,用能谱仪分析了各微区的成分变化,测量了燃烧温度和燃烧波蔓延速度,并用XRD分析了反应产物相的组成.结果表明,Ti-C-Al系燃烧反应起始于铝粉熔化后与固态钛粉反应生成Al3Ti,并随着反应温度的升高,TiC颗粒从溶有钛和碳的铝熔体中析出;当Al3Ti熔化后,从熔体中也析出TiC颗粒,最终产物组织中除大量的TiC颗粒分布于铝基体中外,还发现有少量的Al3Ti存在,可能与使用的钛粉和铝粉的原料颗粒较粗有关.

Microstructural evolution during self-propagating high temperature synthesis of TiC-Al cermet

Through the combustion front quenching method, the microstructural evolution during self-propagating high temperature synthesis of TiC-Al cermet was studied, and the unreucted zone, reacting zone and reacted zone were remained in the quenched sample. The process of microstructure conversion in the quenched sample was observed with scanning electron microscope and energy dispersive spectrometer. The phase constituents of product were analyzed by XRD, and the combustion temperature and the propagating rate of combustion wave were measured. The results show that the combustion reaction among Ti, C and Al starts with the melting of Al and formation of Al_3Ti, Ti and C gradually dissolve into the Al liquid solution, and TiC particles precipitate from the Ti-Al-C melt with the temperature rising, and TiC particles also precipitate from the melt after Al_3Ti melting. In the final product, a large amount of TiC particles distribute on the Al matrix and a small amount of Al_3Ti exist. This imcompleteness of the combution reaction attributes to the coarser Ti and Al powders.