Fabrication of a TiC/Ti5Si3 nano-grained composite for micro-parts by pseudo-superplastic deformation

Abstract

Ceramics composites are suitable as the materials for a micro electro mechanical system (MEMS) parts in terms of its mechanical and physical properties. We apply the PM process in combination with mechanical alloying (MA) and Spark Plasma Sintering (SPS) to produce micro-parts using a ceramic composite, TiC/Ti5Si3. Powders of elements Ti and SiC whose composition is Ti-20mass%SiC are blended for MA. After the alloying, the MA powder whose average particle size is 20-30 μm, has amorphous-like structures. Results of compression-tests and TEM observations indicate the occurrence of unusual high-temperature deformation behaviors such as low flow stress at the lower deformation temperature. The deformation is attributed to a pseudo-superplasticity in which the phase transition of metastable microstructure occurs during the deformation. The pseudo-superplasticity observed in the SPS compact improves the formability in fabrication of the micro-parts. The MA powder is filled into a micro-size mold produced by LIGA process, and casts together by SPS in order to fabricate a new micro-parts using TiC/Ti5Si3. Optimization of the pseudo-superplasticity enables the fabrication of the micro-parts using TiC/Ti5Si 3.