Resistance sintering of CoCrFeNiAlx (x=0.7, 0.85, 1) high entropy alloys: Microstructural characterization, oxidation and corrosion properties
Resistance sintering of CoCrFeNiAlx (x=0.7, 0.85, 1) high entropy alloys: Microstructural characterization, oxidation and corrosion properties
复制标题
DOI：
10.1016/j.jallcom.2021.160180
复制
发表时间：
2021-05-13
影响因子：
6.2
通讯作者：
Ozdemir, O.
中科院分区：
文献类型：
--
作者：
Garip, Y.;Ergin, N.;Ozdemir, O.
研究了电阻烧结CoCrFeNiAlx（x = 0.7，0.85和1mol）高熵合金的循环氧化和电化学腐蚀行为。根据这项工作的目的，CoCrFeNiAlx HEAs与不同的Al含量的循环氧化温度为800，875和950摄氏度为120小时，并在0.5 M的H2SO4和3.5重量%的NaCl溶液中的腐蚀性能进行了评估，使用动电位极化。X射线衍射分析结果表明，BCC和FCC相沿着与少量的B2相形成在所有三个HEA。当Al含量从0.7mol增加到1mol时，BCC相分数增加了34.7%，同时显微硬度增加了22.6%。Al含量的增加对提高CoCrFeNiAlx HEAs的抗循环氧化性能有显著影响。所有氧化HEAs的氧化速率增加，无论是增加温度或减少Al含量。CoCrFeNiAl HEA在800 ℃、875 ℃和950 ℃的温度下观察到最佳抗氧化性，其在120小时暴露期间具有最小的重量变化数据。XRD分析结果表明，氧化120 h后，HEAs表面形成的主要氧化物为Al2O3和Cr2O3。横截面显微照片表明，厚度和连续性的氧化皮上形成的HEAs强烈依赖于Al含量。HEAs氧化性能的改善是由于Al含量的增加，导致氧化膜中Al2O3含量增加。在所进行的氧化持续时间内，既没有开裂也没有剥落的氧化皮被目击。铝的影响表现出相反的模式在HEAs的氧化和腐蚀行为。在3.5wt%NaCl和0.5M H2SO4溶液中，具有最高Al的HEA在HEA中表现出更差的耐腐蚀性，反映在更负的腐蚀电位和更高的腐蚀电流密度以及更高的腐蚀速率。腐蚀行为的恶化归因于由于Al含量的增加而增加的BCC相分数。(C)2021爱思唯尔有限公司版权所有。
The cyclic oxidation and electrochemical corrosion behaviors of CoCrFeNiAlx (x = 0.7, 0.85 and 1 mol) high entropy alloys (HEAs) produced by resistance sintering were explored. In accordance with the purpose of this work, CoCrFeNiAlx HEAs with different Al content were cyclically oxidized at temperatures of 800, 875 and 950 degrees C for 120 h, and their corrosion performances in 0.5 M H2SO4 and 3.5 wt% NaCl solutions were assessed using the potentiodynamic polarization. X-ray diffraction analysis results revealed that BCC and FCC phases along with a minor B2 phase formed in all three HEAs. When the Al content increased to 1 mol from 0.7 mol, the phase fraction of BCC increased by 34.7%, accompanied by an increase in microhardness by 22.6%. The increased Al content had a significant effect in enhancing the cyclic oxidation resistance of CoCrFeNiAlx HEAs. The oxidation rate of all the oxidized HEAs increases with either increasing temperature or decreasing Al content. The best oxidation resistance at temperatures of 800 degrees C, 875 degrees C and 950 degrees C was observed with CoCrFeNiAl HEA, which had minimum weight change data during 120 h of exposure. XRD analysis results revealed that Al2O3 and Cr2O3 were the main oxides that formed on surfaces of the HEAs after oxidation for 120 h. Cross-sectional micrographs showed that the thickness and continuity of oxide scales that formed on HEAs were strongly dependent on the Al content. The improved oxidation behavior of HEAs was attributed to the rise in Al content, which causes the increasing Al2O3 content in oxide scale. Over the performed oxidation duration, neither cracking nor spalling of the oxide scales was witnessed. The effect of Al exhibited a contrary pattern in terms of the oxidation and corrosion behaviors of HEAs. In both 3.5 wt% NaCl and 0.5 M H2SO4 solutions the HEA with the highest Al showed worse corrosion resistance among the HEAs, reflected in the more negative corrosion potential and higher corrosion current density as well as higher corrosion rate. The worsening of the corrosion behavior has been attributed to the increased phase fraction of BCC due to the increased Al content. (C) 2021 Elsevier B.V. All rights reserved.