TiC phase in Ti alloys at different temperatures
(1. School of Materials Science and Engineering,
Harbin Institute of Technology(Weihai), Weihai 264209, China;
2. School of Materials Science and Engineering,
Harbin Institute of Technology, Harbin 150001, China)
Harbin Institute of Technology(Weihai), Weihai 264209, China;
2. School of Materials Science and Engineering,
Harbin Institute of Technology, Harbin 150001, China)
Abstract: Ti-11Al alloys with C content up to 1.5%(mass fraction) were prepared by melt-casting processing. Phase equilibria and TiC transformations were studied using optical and scanning electron microscopy and X-ray diffractometry. As-solidified Ti-11Al alloy with 0.5%C consists of α-Ti, α2-Ti3Al and TiC, and with increasing C content, these phases change into α2-Ti3Al, TiC and Ti3AlC, respectively. TiC is in equilibrium with β-Ti at 1250℃. However, Ti3AlC is in equilibrium with α-Ti and α-Ti+α2-Ti3Al when the alloys are heat treated at 1050℃ and 750℃ respectively. TiC phase in as-solidified Ti-11Al-1.5C alloy dissolves and precipitates as thin elongated Ti3AlC plates after holding at 1050℃ and 750℃ for a long time. Thin elongated Ti3AlC plates precipitate along specific crystallographic orientation and are parallel to each other.
Key words: Ti alloy; heat treatment; TiC transformation; Ti3AlC