High Temperature Deformation Behavior and Microstructure Change in Nano-Grain Ti-SiC Composites
Naoki MIYANO Yusuke KUMAGAI Masayoshi YOSHIMOTO Kazuo ISONISHI and Kei AMEYAMA
Abstract:Ti-SiC nano grain composite is produced by sintering process by using mechanical alloyed powder. Then, its high temperature transformation behavior and the microstructure change of non-equilibrium structures are investigated. TiC/Ti5Si3 powders of elements Ti and SiC whose composition is Ti-20mass%SiC are blended for mechanical alloying(MA). The MA powder whose average particle size is 20~30 ?m, has an amorphous structure. The MA powder is compacted by cold compact compression machine for fabrication of a compression-test piece. As the results of the compression-test and TEM observations, it found that new phases were forming during the compression test, and the flow stress changed depending on the initial microstructure of a test piece. Especially, the existence of Ti3SiC2 and a SiC phase affected deformation resistance. Such a deformation behavior is attributed to a pseudo-superplasticity in the material, in which the phase transition of metastable microstructure occurs during the deformation. Key Words:Mechanical alloying, Non-equilibrium, Ceramics composite, Superplastic deformation, SPS