Promoting the mechanical properties of Ti42Al9V0.3Y alloy by hot extrusion in the α plus β phase region

Hot extrusion was conducted in the alpha+beta phase region for promoting mechanical properties of Ti42Al9V0.3Y. The microstructures and tensile properties before and after hot extrusion were studied. The results show that the microstructure of the as-cast alloy mainly consists of massive gamma phase in beta matrix and the as-extruded alloy mainly consists of lamellar alpha(2)/gamma, lamellar beta/gamma, and strip gamma propagating from elongated beta phase. In the as-cast alloy, the predominantly observed fracture mode is transgranular cleavage failure at room temperature and intergranular fracture at 650-750 degrees C. After hot extrusion, it transforms into transgranular cleavage-like failure, including translamellar cleavage and delamination. The excellent tensile properties of the as-extruded material are attributed to the obvious refined microstructure with broken YAl2 particles and the micro-crack shielding action of the TiAl lamellasome.