Microstructural evolution during extrusion of a Ti/Al/Al35V65 (Ti-6Al-4V) powder compact and the mechanical properties of the extruded rod

The microstructural evolution during extrusion of a powder mixture of HDH Ti, Al and Al35V65 master alloy powders with a nominal composition Ti-6Al-4V(wt%) at 1300 °C and the mechanical properties of the extruded rod were studied. The results show that the amount of plastic deformation of the powder particles has a significant effect on the dissolution of the Al35V65 master alloy particles which in turn significantly influences the microstructure, mechanical properties and fracture behaviour of the extruded rod. The Al35V65 master alloy particles are completely dissolved in the material passing through the extrusion die orifice due to the large amount of powder particle deformation, while a large fraction of the Al35V65 master alloy particles are not dissolved in the undeformed regions close to the top of and in the dead zone of the as-sintered compact being extruded. The average yield strength, ultimate tensile strength and elongation to fracture of the as-extruded Ti-6Al-4V alloy rod are 1255 MPa, 1300 MPa and 7.1%, respectively, which are comparable to those of Ti-6Al-4V alloy produced by conventional methods. The fracture behaviour of the Ti-6Al-4V alloy during tensile testing is also examined and discussed.