Effect of hafnium content on the microstructural evolution and stress rupture properties of K4750 nickel-based superalloy
Effect of hafnium content on the microstructural evolution and stress rupture properties of K4750 nickel-based superalloy
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DOI：
10.1016/j.jallcom.2022.165473
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发表时间：
2022-05
影响因子：
6.2
通讯作者：
Meiqiong Ou;Yingche Ma;Kunlei Hou;Kui Liu
中科院分区：
文献类型：
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作者：
Meiqiong Ou;Yingche Ma;Kunlei Hou;Kui Liu
通过热力学计算和实验研究了不同铪含量的K4750镍基高温合金的组织演变。TC分析表明，随着Hf含量从0wt%增加到1.5wt%，MC碳化物的再溶解温度先迅速降低后趋于稳定，M23 C6碳化物的析出温度逐渐降低，γ′质量分数先升高后趋于稳定。然后制备含有0重量%、0.11重量%和0.28重量% Hf的三种合金以进一步研究微观结构的演变。结果表明，随着Hf含量的增加，MC碳化物的形貌由长条状变为棒状和块状，这是由于MC碳化物中Ti、Nb含量的减少和Hf含量的增加造成的。Hf的加入也改变了M23 C6碳化物的形态，从连续到粒状，由于不同的MC分布在晶界（GB）。此外，少量Hf偏聚到γ′相中，降低了γ′相中Al和Nb的含量，导致γ/γ′晶格失配增大。随着Hf含量从0wt%增加到0.11wt%和0.28wt%，750 °C和430 MPa下的平均持久寿命从99.54 h增加到105.73 h和170.96 h，这与MC、M23 C6和γ′相的演变密切相关。因此，详细讨论了显微组织与持久性能之间的关系。
The microstructural evolution of K4750 nickel-based superalloy with different hafnium (Hf) contents was investigated by thermodynamic calculations (TC) and experiments. According to TC, with the increases of Hf content from 0 wt% to 1.5 wt%, the redissolving temperature of MC carbide first decreased rapidly and then tended to be relatively stable, the precipitated temperature of M23C6carbide decreased gradually, while the γ′ weight fraction increased first and then stabilized. Three alloys containing 0 wt%, 0.11 wt%, and 0.28 wt% Hf were then prepared to further study the evolution of the microstructure. The experimental results showed that the increase of Hf content changed the morphology of MC carbide from long strip to rodlike and blocky, which is caused by the decrease of Ti and Nb contents and the increase of Hf content in MC carbides. The addition of Hf also changed the morphology of M23C6carbide from continuous to granular due to the different MC distribution at grain boundaries (GBs). In addition, a small amount of Hf segregated into the γ′ phase, reducing the Al and Nb contents of the γ′ phase, resulting in an increased γ/γ′ lattice mismatch. As the Hf content increased from 0 wt% to 0.11 wt% and 0.28 wt%, the mean stress rupture life at 750 °C and 430 MPa increased from 99.54 h to 105.73 h and 170.96 h, which was closely related to the evolution of MC, M23C6and γ′ precipitates. Therefore, the relationship between microstructure and stress rupture properties was discussed in detail.