Investigation of the structure and morphology of hardening phases in the niobium 5VMTs alloy at high temperature aging

The stability of the structure of a recrystallized 5VHTs niobium alloy in the course of prolonged high-temperature holding in vacuum under stressed state was studied. Using optical and transmission electron microscopy techniques. Investigated was sheet deformed material after a recrystallizing annealing at 1400 deg C for 1 h with subsequent aging at 900 and 1100 deg C. The investigation indicated that the aging of the 5VMTs alloy at 900 and 1100 deg C involves a partial dissolution of disperse carbides of ZrC and Nb2C and their fragmentation. MeC type carbides of globular shape, the amount of which remained almost without variation on increase of the aging time to 5000 h, are produced at 1100 deg C after several hundreds of hours