The sintering densification, microstructure and mechanical properties of Ti–48Al–2Cr–2Nb by a small addition of Sn–Al powder

Abstract

TiAl alloys are difficult to obtain high density through traditional pressing and sintering process. Sn is a promising liquid-phase sintering addition for TiAl alloys; however, the further studies have elaborated that the liquid phase sintering of Sn is limited due to poor wettability between TiAl and melt Sn. Based on it, this study adopts Sn–Al powder addition instead of pure Sn powder. The results describe that a small amount of active Al enhanced the wettability of the Sn droplets to the TiAl matrix, thereby further promoting the liquid phase sintering effect of the addition of Sn. The sample sintered at 1320–1350 °C has a density excess of 95%, near γ or duplex microstructure with small proportion of lamellar colonies. Through subsequent non-encapsulation HIP, the fine-grained structure is maintained at the same time to reach full density, which enables the as-sintered samples to obtain moderate tensile properties at room temperatures (UST = 520 ± 5 MPa, YS = 401 ± 7 MPa, EL = 1.33 ± 0.1).

Keywords

• Titanium aluminide
• Liquid sintering
• Wettability
• Microstructure
• Mechanical properties