Room and high temperature mechanical behavior of Ti–Al–Nb–Mo alloy reinforced with Ti2AlN ceramic particles

Abstract

In order to improve the room and high temperature mechanical properties of Ti46Al4Nb1Mo alloy, Ti46Al4Nb1Mo-xN (x = 0, 0.4%, 0.8%, 1.2%, 1.6%, atomic percent, hereafter in at.%) alloys were prepared by adding TiN powders. Results showed that when the N addition was more than 0.8%, the grain morphology changed from columnar dendrites to equiaxed grains due to the formation of Ti2AlN particles, and the equiaxed grain size decreased with further increasing of the N addition. With 1.6% N addition, the compressive strength increased by 16.8% at room temperature, which was due to the collective strengthening effect of lamellae refinement and Ti2AlN particles. While lamellae refinement and Ti2AlN particles had opposite effects and competed with each other at high temperature, strengthening by Ti2AlN particles had the dominant effect on improving the peak stress of the Ti46Al4Nb1Mo-1.6 N alloy, which increased by 21.8% and 24.1% at 900 °C and 1000 °C, respectively. In addition, compared with the fracture microstructure at room temperature, the deformed microstructure showed that the load transfer effect of Ti2AlN particles was more effective at high temperature, which was due to micro-damages in the Ti2AlN particles and the absence of cracks along irregular Ti2AlN particles.