Cr/Fe含量对AlCoCrFeNi_(2.1)共晶高熵合金微观组织和腐蚀性能的影响  

Effect of Cr/Fe on the Microstructure and Corrosion Behaviors of AlCoCrFeNi_(2.1) Eutectic High-entropy Alloy

作　　者：陈晨 安煜东 姚宏伟 蒲吉斌 CHEN Chen;AN Yudong;YAO Hongwei;PU Jibin(School of Materials Science and Engineering,Taiyuan University of Science and Technology,Taiyuan 030024,China;Key Laboratory of Advanced Marine Materials,Ningbo Institute of Materials Technology and Engineering,Chinese Academy of Sciences,Ningbo 315201,China;Qianwan Institute of CNITECH,Ningbo 315336,China)

机构地区：[1]太原科技大学材料科学与工程学院,太原030024 [2]中国科学院宁波材料技术与工程研究所海洋关键材料重点实验室,宁波315201 [3]宁波杭州湾新材料研究院,宁波315336

出　　处：《中国表面工程》2024年第6期343-353,共11页China Surface Engineering

基　　金：国家杰出青年科学基金(52325503);宁波市自然科学基金一般项目(2023J328)。

摘　　要：AlCoCrFeNi_(2.1)共晶高熵合金由面心立方无序固溶体相(FCC)和体心立方有序相(B2)形成交替片层结构,具有良好的铸造性能和强韧性。然而,在NaCl溶液电化学腐蚀过程中,B2相的富Al钝化膜比FCC相的富Cr钝化膜稳定性差,导致B2相较快溶解,发生局部腐蚀。通过相图计算法(CALPHAD)设计AlCoCr_(1+x)Fe_(1-x)Ni_(2.1)高熵合金,通过提高Cr/Fe元素比来调控合金的微观组织和耐腐蚀性能。与铸态AlCoCrFeNi_(2.1)合金相比,铸态AlCoCr_(1.5)Fe_(0.5)Ni_(2.1)合金中硬质B2/BCC双相的体积分数由27.2%提升至42.6%,其中体心立方结构(BCC)富Cr纳米相的体积分数为19.8%,其维氏显微硬度提高了8.6%,在3.5wt.%NaCl溶液中的腐蚀电流密度降低了35.5%。因此,通过成分设计在贫Cr的B2相中大量析出富Cr共格纳米相,实现硬度和耐腐蚀性能的协同提升。研究成果为高强度与耐腐蚀一体化高熵合金的开发提供了新策略。In recent years,high-entropy alloys (HEAs) have attracted considerable attention owing to their outstanding properties and distinctive design concepts of multiple principal elements.HEAs often crystallize into simple structures,including face-centred-cubic(FCC) and body-centred-cubic (BCC).However,HEAs with single-phase FCC structures exhibit higher ductility but lower strength,whereas those with single-phase BCC structures tend to exhibit limited ductility.To simultaneously achieve high strength and good ductility,the concept of eutectic high-entropy alloys (EHEAs) has been proposed.The Al Co Cr Fe Ni_(2.1) EHEA demonstrated exceptional strength-ductility correlation and castability owing to its complete lamellar eutectic structure,which consisted of a soft FCC phase and a hard B2 phase.Notably,eutectic crystallization resulted in an uneven distribution of elements in the Al Co Cr Fe Ni_(2.1)EHEA.Specifically,Cr was enriched in the FCC phase,and Al was enriched in the B2 phase.While both Al and Cr are prone to form a compact oxide film,the Al-rich passivation film of the B2 phase is less stable than the Cr-rich passivation film of the FCC phase during electrochemical corrosion in Na Cl solution.This led to local corrosion in the B2 phase.Numerous studies have shown that Cr in the Al-Co-Cr-Fe-Ni HEA system tends to be distributed in both the FCC and BCC phases.Therefore,an increase in Cr can promote the formation of a Cr-rich BCC phase,which can form a dense passivation film,thereby improving corrosion resistance.In this study,the effects of Cr and Fe on the microstructural evolution and corrosion performance of the Al Co Cr Fe Ni_(2.1) EHEA were systematically investigated.As-cast Al Co Cr_(1+x)Fe_(1-x)Ni_(2.1) (x=0,0.3,0.5) alloys were designed using the calculation of phase diagrams(CALPHAD).The ingots were synthesized by vacuum arc melting of the raw elements (with a weight percentage purity≥99.9%)under an argon atmosphere.The crystal structures of the as-cast alloys were characterized using an X-ray diffra

关 键 词：高熵合金 相形成 微观组织 硬度 电化学腐蚀 

分 类 号：TG174[金属学及工艺—金属表面处理]