On the Effect of Nb on the Microstructure and Properties of Next Generation Polycrystalline Powder Metallurgy Ni-Based Superalloys
On the Effect of Nb on the Microstructure and Properties of Next Generation Polycrystalline Powder Metallurgy Ni-Based Superalloys
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DOI：
10.1007/s11661-018-4682-4
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发表时间：
2018-09-01
影响因子：
2.8
通讯作者：
Stone, Howard J.
中科院分区：
文献类型：
--
作者：
Christofidou, Katerina A.;Hardy, Mark C.;Stone, Howard J.
研究了Nb对两种新型粉末冶金镍基高温合金性能和组织的影响，并与劳斯莱斯RR1000合金进行了对比。与RR1000和不含Nb的合金相比，含Nb的合金表现出更好的拉伸和蠕变性能以及更好的抗氧化性。Nb对拉伸和蠕变性能的有利影响是由于固溶后热处理后获得的显微组织，这导致了更高的伽马‘体积分数和更细小的三级伽马’分布。此外，随着Nb的加入，伽马‘相的反相界能也有望增加，从而进一步提高材料的强度。然而，伽马分布中的这些修改对材料的驻留疲劳裂纹扩展行为产生了不利影响，尽管这种行为可以通过修改热处理来改善。含Nb合金的抗氧化性也得到了提高，因为Nb被认为能加速形成无缺陷的Cr2O_3氧化膜。总体而言，无论是否添加Nb，两种开发合金都表现出比RR1000更好的性能。
The effect of Nb on the properties and microstructure of two novel powder metallurgy (P/M) Ni-based superalloys was evaluated, and the results critically compared with the Rolls-Royce alloy RR1000. The Nb-containing alloy was found to exhibit improved tensile and creep properties as well as superior oxidation resistance compared with both RR1000 and the Nb-free variant tested. The beneficial effect of Nb on the tensile and creep properties was due to the microstructures obtained following the post-solution heat treatments, which led to a higher gamma' volume fraction and a finer tertiary gamma' distribution. In addition, an increase in the anti-phase-boundary energy of the gamma' phase is also expected with the addition of Nb, further contributing to the strength of the material. However, these modifications in the gamma' distribution detrimentally affect the dwell fatigue crack-growth behavior of the material, although this behavior can be improved through modified heat treatments. The oxidation resistance of the Nb-containing alloy was also enhanced as Nb is believed to accelerate the formation of a defect-free Cr2O3 scale. Overall, both developmental alloys, with and without the addition of Nb, were found to exhibit superior properties than RR1000.