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

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 alpha(2)/gamma lamellar colonies with a mean size of about 100 mu m, and minor gamma as well as beta 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 degrees C 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 25 mu m, 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 degrees C increases to 716MPa with the elongation of 3.6%.