Microstructure and high temperature tensile properties of Ti22Al25Nb alloy prepared by reactive sintering with element powders

The Ti22Al25Nb alloy was prepared by reactive sintering with element powders. The reactive sintering process was conducted by step reactive sintering in order to prevent loss of Al; thus, the process was performed at 903 K, holding 60 min and 20 MPa, and then increased to 1523 K for 120 min and 30 MPa, followed by furnace cooling. The O (orthorhombic Ti2AlNb) phase and B2 phase were obtained in the sintered Ti22Al25Nb alloy, and a few Ti3Al phases. Subsequently, the microstructures and phases of the sintered alloy were analyzed at two sintering stages. Moreover, the forming mechanism of O (orthorhombic Ti2AlNb) phase and reactive mechanism were analyzed. In view of examining the tensile property, the tensile tests were carried out from 1233 K to1313 K at an interval of 20 K. The tensile datum indicated that the elongations increased with the increasing temperature and decreasing strain rate; the tensile strength decreased with increasing temperature and decreasing strain rate. From the experimental results, the maximum elongation of the sintered alloys was up to 146% at 1313 K at1.04×10−4 s−1, and tensile strength was above 85 MPa.