Oxidation of CoCrFeMnNi High Entropy Alloys
Oxidation of CoCrFeMnNi High Entropy Alloys
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DOI：
10.1007/s11837-015-1517-2
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发表时间：
2015-10-01
期刊：
影响因子：
2.6
通讯作者：
Carney, Casey
中科院分区：
文献类型：
--
作者：
Holcomb, Gordon R.;Tylczak, Joseph;Carney, Casey
制备了CoCrFeMnNi族中的八种模型高熵合金（HEAs）（包括CoCrFeNi和CoFeMnNi亚族中各一种合金），并在650 A ℃和750 A ℃下暴露于实验室空气中1100 h。两种商业合金，镍基高温合金230（N 06230）和奥氏体不锈钢304 H（S30409），同时暴露进行比较。质量变化的氧化动力学进行了测量和暴露的样品的横截面进行了观察。这些HEA中的七种含有更多的Mn（12-24重量%）。比在商业耐热不锈钢和超级合金中发现的更高。CoCrFeNi的抗氧化性优异，在650 A ℃下与304 H相当，在750 A ℃下仅略差。CoCrFeNi上的薄氧化皮主要是Cr氧化物（推测为Cr2 O3），在氧化皮的外部有一些Mn氧化物。CoCrFeMnNi HEAs都经历了比CoCrFeNi更快的氧化，特别是在750 A ℃时，经历了氧化皮剥落。在合金中添加Y以降低S提高了这些HEAs的抗氧化性。合金CoFeMnNi，没有铬，经历了更高的氧化速率和规模spectrometry比含铬合金。抛物线速率常数log（k（p））作为wt.%的函数的线性回归分析Cr和Mn发现了氧化速率常数的组成依赖性的良好相关性，特别是在650 A摄氏度。Mn增加log（k（p））比Cr降低log（k（p））更有害。如果CoCrFeMnNi HEAs用于高温氧化环境，则应在保持Cr水平的同时检查较低的Mn水平。
Eight model high entropy alloys (HEAs) in the CoCrFeMnNi family (including one alloy each in the CoCrFeNi and CoFeMnNi subfamilies) were made, prepared, and exposed to laboratory air for 1100 h at 650A degrees C and 750A degrees C. Two commercial alloys, nickel-base superalloy 230 (N06230) and austenitic stainless steel 304H (S30409), were simultaneously exposed for comparison. Mass change oxidation kinetics were measured and cross-sections of exposed samples were observed. Seven of these HEAs contained much more Mn (12-24 wt.%) than is found in commercial heat-resistant stainless steels and superalloys. The oxidation resistance of CoCrFeNi was excellent and comparable to 304H at 650A degrees C and only slightly worse at 750A degrees C. The thin oxide scale on CoCrFeNi was primarily Cr oxide (presumably Cr2O3) with some Mn oxide at the outer part of the scale. The CoCrFeMnNi HEAs all experienced more rapid oxidation than CoCrFeNi and, especially at 750A degrees C, experienced oxide scale spallation. The addition of Y in the alloy to lower S improved the oxidation resistance of these HEAs. Alloy CoFeMnNi, without Cr, experienced much higher oxidation rates and scale spallation than the Cr-containing alloys. A linear regression analysis of the log of the parabolic rate constant, log(k(p)), as functions of wt.% Cr and Mn found a good correlation for the compositional dependence of the oxidation rate constant, especially at 650A degrees C. Mn was found to be more detrimental increasing log(k (p)) than Cr was helpful reducing log(k (p)). If CoCrFeMnNi HEAs are to be used in high temperature oxidizing environments, then examining lower levels of Mn, while maintaining Cr levels, should be pursued.