Hf对Nb15W5Si2B合金室温和高温力学性能的影响

 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Nb-SS占主导的Nb15W5Si2BxHf(x= 0，5，10，15,原子百分数）合金，研究了Hf元素对Nb15W5Si2B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，Nb15W5Si2B合金由Nb-SS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Nb15W5Si2B合金的高温静强度和室温塑性，但对Nb15W5Si2B高温压缩蠕变性能不利。最后讨论了Hf对Nb15W5Si2B合金强化与塑性化机理。

Effects of Hf on Mechanical Properties of Nb-15W-5Si-2B Alloy at Room-temperature and High-temperature

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 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.