Abstract:

To probe balance between room-temperature plasticity and high-temperature strength of Nb-Si based alloys, Nb15W5Si2BxHf(x=0,5,10,15 at%) alloys with an Nb-SS dominant microstructure were developed, and the effects of Hf addition on the microstructure and mechanical properties of Nb5Si15W2BxHf at room-temperature and high-temperature were investigated and compared. The results show that the microstructure of the Nb15W5Si2B is composed of the Nb-SS matrix and the network Nb5Si3; the Hf addition does not change the phase constitution, however, with an Hf addition the morphology of the Nb5Si3 phase becomes islands gradually and the Nb5Si3 fraction decreases. Both the high-temperature compression strength and the room-temperature plasticity of the Nb-15W-5Si-2B alloy are improved by the Hf addition at the same time. However, Hf is harmful for creep behavior at high-temperature. Finally, the strengthening and ductilizating mechanisms of Hf on the Nb-15W-5Si-2B alloy are primarily discussed.

Key words: Nb-Si , alloy,  , element , Hf,  , hightemperature , strength,  , room-temperature , plasticity,  , creep , behavior