中文摘要：

为了寻求Nb-Si基合金高温强度和室温塑性之间的平衡，设计了以Nb基固溶体相Nbss占主导的Nb-15W-5Si-2B-xHf（x=0，5，10，15，原子百分数）合金，研究了Hf元素对Nb-15W-5Si-2B合金的组织、室温和高温压缩性能以及高温蠕变性能的影响。结果表明，Nb-15W-5Si-2B合金由Nbss和Nb5Si3两相组成，Nb5Si3相呈网状分布；Hf的加入不改变相组成，但Nb5Si3相由网状分布逐步变成不连续小岛状分布，而且体积分数减少。Hf同时提高Nb-15W-5Si-2B合金的高温静强度和室温塑性，但对Nb-15W-5Si-2B高温压缩蠕变性能不利。最后讨论了Hf对Nb-15W-5Si-2B合金强化与塑性化机理。

英文摘要：

To probe balance between room temperature plasticity and high temperature strength of Nb-Si based alloys, Nb-15W-5Si-2B-xHf（x = 0,5,10,15 at%）alloys with an Nbss-dominant microstructure were developed, and the effects of Hf addition on the microstructure and mechanical properties of Nb-5Si-15W-2B-xHf at room-temperature and high temperature were investigated and compared. The results show that the microstructure of the Nb-15W-5Si-2B is composed of the Nbss matrix and the network Nb5Si3 ; the Hf addition does not change the phase constitution, however, with an Hf addition the morphology of the Nb5 Si3 phase becomes islands gradually and the Nb5 Si3 fraction decreases. Both the hightemperature 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 duetilizating mechanisms of Hf on the Nb-15 W-5 Si-2B alloy are primarily discussed.