Zheng Ming Sun

Synthesis of single-phase Ti3SiC2 powder

Abstract In this study, free 2Ti/2Si/3TiC powder mixture was heated at high temperatures in vacuum, in order to reveal the possibility for the synthesis of high Ti 3 SiC 2 content powder. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used for the evaluation of phase identities and the morphology of the powder after different treatments. Results showed that almost single phase Ti 3 SiC 2 powder (99.3 wt.%) can be synthesized by heat treatment with free 2Ti/2Si/3TiC powders in vacuum at 1210°C for about 3 h. The nucleation and growth of Ti 3 SiC 2 within TiC particles was observed. The typical appearance of the formed Ti 3 SiC 2 is equiaxed with particle size of 2–4 μm. Effects of temperature and heating time on the morphology and the particle sizes of the synthesized Ti 3 SiC 2 powders are not obvious.

Synthesis and consolidation of TiAl by MA–PDS process from sponge-Ti and chip-Al

Abstract Low cost sponge-Ti and recycled chip-Al were used as starting materials for the synthesis and consolidation of TiAl alloy via a mechanical alloying (MA) and pulse discharge sintering (PDS) process. Amorphous structured TiAl powder was obtained by MA process from sponge-Ti/chip-Al and was sintered and concurrently consolidated with the PDS process. The obtained TiAl alloy consists of γ-TiAl and α2-Ti3Al and additional Ti2AlC phase. The microstructure of the alloy can be controlled by the sintering temperature. It was found that fine equiaxed grains were obtained by low temperature sintering while fine duplex structures formed at high temperature sintering. Compared with alloys fabricated from high cost elemental Ti/Al powder with a similar process, the alloys sintered at high temperature with this process possess much higher strength at both room temperature and elevated temperatures.