Microstructure and Mechanical Properties of Hot Deformed Ti-45Al-7Nb-0.3W Alloy

Abstract

Microstructure and mechanical properties of hot deformed (as-forged,as-rolled) Ti-45Al-7Nb-0.3W(atom fraction/%) alloy were investigated by optical microscope (OM), scanning electron microscope(SEM), transmission electron microscope(TEM) and tensile testing. Results show that the microstructure of as-cast Ti-45Al-7Nb-0.3W alloy is near lamellar, which is mainly composed of α2/γ lamellar colonies with a mean size of about 100μm,and minor γ as well as β phases located along the lamellar colonies boundaries. After hot canned forging, the lamellar colonies are broken and kinked. Compared with the as-cast alloy, the tensile strength of current as-forged alloy at room temperature increases by 77MPa, and the tensile strength at 800℃ increases by 36MPa. After the subsequent hot-pack rolling, the microstructure of the as-forged alloy is transformed into fine duplex microstructure with an average grain size of 25μm, mechanical properties of current as-rolled alloy are further improved, the room temperature tensile strength increases to 603MPa with the elongations of 1.0%, the tensile strength at 800℃ increases to 716MPa with the elongation of 3.6%.

Keywords

• TiAl alloy
• canned forging
• canned rolling
• microstructure
• mechanical property