High Temperature Deformation Behavior, Microstructure and Properties of Novel Multiphase TiAl–(Cr, Nb, Mo) Alloy
LIU Hongwu 1,2 , GAO Fan 1,2 , FENG Xiangzheng 1,2 , LI Zhenxi 1,2
1. Aviation Key Laboratory of Science and Technology on Advanced Titanium Alloys, AECC Beijing Institute of Aeronautical Materials, Beijing 100095, China;
2. Aviation Key Laboratory on Advanced Titanium Alloys of AECC, Beijing 100095, China
Abstract:The hot deformation behavior and mechanical properties of the novel Ti–43.5Al–6(Cr, Nb, Mo)–0.1B alloy were investigated by hot compression tests and hot extrusion. It was indicated that at the temperature range of 1100–1250℃ and strain rate range of 1~0.001s–1 , the samples were all crack-free after compression of 50%. The dissipation coefficient diagram was established at true strain 0.6, low dissipation coefficient area (η<0.3) was mainly distributed in 1100–1180℃ with strain rate 0.1–1s–1. High dissipation coefficient area (η>0.55) was mainly distributed in 1160–1250℃ with strain rate 0.01–0.001s–1 . After Tγ→0–80℃ extrusion + heat treatment, the duplex structure was obtained. The tensile strength was 855MPa and the elongation was 1.0%. After Tγ→0–10℃ extrusion + 900℃/6h/FC treatment, the nearly-lamellar microstructure was obtained. The lamellar orientation preferentially distributed along the extrusion direction. At room temperature, the tensile strength of the as-extruded alloy was 1020MPa and the tensile ductility was 2.0%, the tensile strength is 685MPa at 800℃, demonstrating a good combination of high strength and ductility.