Abstract
The flow softening behaviors of a Nb-Si based ultrahigh temperature alloy during hot compression to height reductions of 10, 30 and 60% respectively at 1410 °C have been investigated. The flow characteristics during dynamic softening of the alloy have been revealed. The evolution of deformed microstructure during compression is that the coupled Nbss/Nb5Si3 eutectics have been gradually broken down accompanied by the development of continuous Nbss matrix with evenly dispersed silicide particles. The softening mechanisms of the Nb-Si based ultrahigh temperature alloy have been discussed based on the orientation variation of both Nbss and Nb5Si3 phases, the deformed microstructure and its flow characteristics. The softening of the alloy is mainly dominated by the continuous dynamic recrystallization (CDRX) of Nbss. The CDRX of Nb5Si3 has occurred at a much more sluggish rate and has just been significantly activated with the height reduction increasing from 30 to 60%. The gradual refinement of silicide particles has been observed with increase in strain.
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