Microstructure and mechanical properties of high relative density γ‐tial alloy using irregular pre‐alloyed powder

Abstract

Preparing high relative density γ‐TiAl alloy by pressure‐less sintering at low‐cost has al-ways been a challenge. Therefore, a new kind of non‐spherical pre‐alloyed TiAl powder was prepared by the reaction of TiH2 powder and Al powder at 800 °C to fabricate high‐density Ti‐48Al alloy via pressure‐less sintering. The oxygen content was controlled to below 1800 ppm by using coarse Al powder (~120 μm). The sintered densities ranged from 92.1% to 97.5% with sintering temperature varying from 1300 °C to 1450 °C. The microstructure of the sintered compact was greatly influenced by the sintering temperature. The as‐sintered samples had a near‐γ structure at 1350 °C, a duplex structure at 1400 °C, and a nearly lamellar structure at 1450 °C. To achieve full densifica-tion, non‐capsule hot isostatic pressing was performed on the 1350 °C and 1400 °C sintered samples. As a result, high compressive strengths of 2241 MPa and 1931MPa were obtained, which were higher than the existing Ti‐48Al alloys.