等离子熔覆制备AlCrFeMnNi高熵合金涂层的微观组织与性能.pdf
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1、Aug.2023CHINA SURFACEENGINEERING2023年8 月No.4Vol.36面国表中第36 卷第4期程doi:10.11933/j.issn.1007-9289.20221103003等离子熔覆制备AICrFeMnNi高炳合金涂层的微观组织与性能王兴涛1吴一凡1孙金峰1孟永强1刘宏伟2(1.河北科技大学河北省柔性功能材料重点实验室石家庄050000;2.河北京津冀再制造产业技术研究有限公司河间062450)摘要:对高熵合金涂层的成分设计已有较多探究,但针对无Co系高熵合金涂层研究较少。采用等离子熔覆技术在E32钢上制备AICrFeMnNi高熵合金涂层,利用金相显微镜、S
2、EM、ED S、XR D 等对涂层的组织形貌、相结构及元素分布等进行观察分析,采用显微硬度计、电化学工作站、XPS表征涂层的硬度分布及耐腐蚀性能。结果表明,等离子熔覆制备的高熵合金涂层无裂纹、气孔等宏观缺陷,涂层为BCC结构;涂层平均硬度为411.6 HVo.5,为基体硬度的2 倍以上;在质量分数3.5%的NaCl溶液中涂层的自腐蚀电位为-0.35V,自腐蚀电流密度为50 7 nA/cm,基体的自腐蚀电位为-0.92 V,自腐蚀电流密度为2 56 A/cm,涂层的自腐蚀电位和极化电流密度较基体有大幅度提升,涂层的固溶强化作用和晶格畸变作用以及BCC结构的螺旋位错强化是提升涂层硬度的原因,均匀的
3、元素分布和致密的钝化膜是其耐蚀性好的主要原因。通过等离子熔覆技术得到高强度、耐腐蚀性好无Co系高摘合金的涂层,可对易制备、低成本的高熵合金涂层的开发、制备和应用提供一定的技术支持。关键词:等离子熔覆;单结构涂层;AICrFeMnNi;微观组织;显微硬度;耐腐蚀性中图分类号:TG174Microstructure and Properties of an AICrFeMnNi High-entropy AlloyCoating Prepared Using Plasma CladdingWANG Xingtao 1WU Yifan!SUN JinfengMENG Yongqiang1LIU Ho
4、ngwei(1.Hebei Key Laboratory of Flexible Functional Materials,Hebei University of Science and Technology,Shijiazhuang 050000,China;2.Institute of Remanufacturing Industry Technology,Jing-Jin-Ji(IRIT),Hejian 062450,China)Abstract:Compared with traditional alloys,high-entropy alloys(HEAs)with simple s
5、tructures exhibit good mechanical propertiesand low corrosion resistance.These unique properties indicate that HEAs can be applied in extreme environments such as hightemperatures,high corrosion,and high wear.However,common HEAs contain expensive and rare metals,which limit theirlarge-scale applicat
6、ion.Because pure metals can no longer satisfy the requirements of future development,an HEA metal compositecomposed of a protective coating of HEA on a metal matrix,in which the HEA act as reinforcement,is expected to enhance theirperformance.To date,many reports have focused on revealing the reinfo
7、rcement mechanism of HEA coatings with Co;however,fewstudies have focused on HEA coatings without Co.In this study,we successfully prepared a series of AICrFeMnNi HEA coatings onan E32 steel matrix using a plasma cladding technique.The effects of composition and structure on the HEA metal composites
8、 werestudied.X-ray difraction,metallographic microscopy,scanning electron microscopy,energy dispersive spectroscopy,andmicrohardness tests were used to characterize the distribution of the elements,microstructure phase,and hardness of the coatings.In*中央引领地方科技发展资金(2 0 6 Z3801G)和河北省重点研发计划支持(192 12 10
9、8 D)资助项目。Fund:Supported by Leading Local Science and Technology Development Fund Project(206Z3801G)and Key Research and Development Program of HebeiProvince(19212108D).20221103收到初稿,2 0 2 2 12 2 2 收到修改稿108面表中2023年程国addition,potentiodynamic polarization curves,electrochemical impedance spectroscopy,an
10、d immersion experiments were performedfor a 3.5%NaCl solution using an electrochemical workstation to determine the corrosion resistance performance.Finally,X-rayphotoelectron spectroscopy was performed on the soaked coatings to analyze the passive film formation.The results showed that theAICrFeMnN
11、i HEA coating prepared using plasma cladding had a BCC structure,which was consistent with the HEA particles used inthis study.No macroscopic defects,such as cracks and pores,occurred at the interface between the HEA coating layer and the metalmatrix,indicating good metallurgical bonding.Because of
12、the dilution of the substrate,the Fe content in the AlCrFeMnNi HEAcoating increased considerably,and the microstructure of the AICrFeMnNi HEA coating changed from columnar dendrites to coarseequiaxed crystals,indicating that an increase in Fe content has a significant effect on the microstructure of
13、 the AICrFeMnNi HEAcoating.The average hardness of the coating was 411.6 HV0.5,which was twice that of the substrate.The enhancement of thehardness can be summarized as follows:First,the disordered atomic distribution of the HEA coating can significantly increase thesolid-solution strengthening and
14、lattice distortion of the coating,thus resulting in superior hardness of the coating.Second,theintrinsic helical dislocations in the BCC structure can significantly increase the hardness of the HEA coating.In addition,the rapidcooling process during plasma cladding positively influence the hardness
15、of the coating.In 3.5 wt.%NaCl solution,the self-corrosionpotential of the AICrFeMnNi HEA coating was-0.35 V and the self-corrosion current density was 507 nA/cm.In comparison,theself-corrosion potential and current density of the substrate were-0.92 V and 256 A/cm,respectively.Both the self-corrosi
16、onpotential and polarization current density of the coating increased significantly compared with those of the substrate,demonstratingexcellent corrosion resistance.The uniform distribution of elements and dense passive film were the main reasons for its superiorcorrosion resistance.Although the AIC
17、rFeMnNi HEA coating exhibited excellent hardness and corrosion resistance,the uncertaintycaused by the dilution of the matrix considerably increased the uncertainty of the structure and properties of the HEA coating.Thus,the contingency resulting from the dilution of the matrix must be explored furt
18、her.Consequently,plasma cladding a non-Co HEAonto a metal matrix can enhance strength and corrosion resistance.This study provides technical support for the development andapplication of large-scale and low-cost high-entropy alloy coatings.Keywords:plasma cladding;single structure coating;AlCrFeMnNi
19、;microstructure;microhardness;corrosion resistance0前言高熵合金(也称多主元合金)主要是指由5种及5种以上组元,每种组元原子百分比在5%35%或结构趋于单一且混型熵高于1.5R(R 为摩尔气体常数)的新型合金-。高的混合炳和多元素的协同作用,使其表现出比传统合金更简单的结构以及更加优异的力学性能和耐腐蚀性能4。在众多高熵合金体系中,具有单一FCC结构、优异的热稳定性和延展性的CoCrFeMnNi系高熵合金在高合金研发中占有重要地位,是很多高熵合金体系开发的基础5-6 ;但其较低的屈服强度和抗拉强度无法满足工业生产加工要求7 ,但通过合理的成分设
20、计可以提高CoCrFeMnNi系高熵合金的强度,ASTAFUROVA等8 通过引入间隙C的方式,增加了CoCrFeMnNi高合金的晶格畸变,大幅度提高了CoCrFeMnNi 高熵合金的强度;SHIM 等9通过氮掺杂,铸态CoCrFeMnNi高熵合金中的沉淀物由相转变为Cr2N,进一步影响了晶粒细化和沉淀强化,提高了CoCrFeMnNi高熵合金的极限抗拉强度、伸长率及应变硬化。因此,由适当的成分设计,可以获得高硬度、高耐磨、高耐蚀等特性组合的高熵合金。除成分设计之外,徐振林等10 发现CoCrFeMnNi高熵合金涂层耐腐蚀性比铸态CoCrFeMnNi高熵合金进一步提升。因此,高熵合金涂层化可进一
21、步发挥高熵合金的性能,同时高熵合金涂层可节约更多原料,更有利于高熵合金的应用。在高合金涂层制备方法中,等离子熔覆技术具有极高的能量密度、快的凝固速度和冷却速度,同时具有设备成本低、操作简单、对工作环境要求低的优点,是一项优秀的涂层制备技术。魏民等12 以等摩尔比Co、Cr、Fe、M n、Ni 粉末为原料,利用等离子熔覆技术在6 5Mn钢上制备出单相结构的FeCoCrNiMn高熵合金涂层;WANG等13 以CoCrFeMnNi高熵合金粉末和金属Ti粉末作原料,制备出由简单固溶体和相组成的(CoCrFeMnNi)sTis高焰合金涂层;YE等14 在Q235钢用等离子熔覆技术制备了仅由FCC、BCC
22、固溶体组成的AICoCrFeMnNi高合金涂层,硬度达5.45GPa,且耐腐蚀性优于30 4不锈钢。以上分析表明,CoCrFeMnNi系高熵合金在制备保护涂层领域具有优秀的开发潜力。但该系高熵合金组成中含有价格昂贵和资源稀缺的Co元素,导致涂层成本增加,因而制备简单、低成本但同时109第4期王兴涛,等:等离子熔覆制备AlCrFeMnNi高熵的微观组织与性能具有优秀综合性能的保护涂层十分必要。在高熵合金常用元素中,A1有助于提高合金表面稳定性,并有利于提高合金的抗氧化性和硬度15,是一种很好的替代Co元素的选择。因此,本文选择AICrFeMnNi高熵合金粉末为原料,利用等离子熔覆技术制备AlCr
23、FeMnNi高熵合金涂层,对其组织结构、硬度、耐蚀性进行系统研究,并从电化学角度对其腐蚀行为进行分析,为研制易制备、低成本、结构简单、高强度、耐腐蚀的保护涂层提供了试验基础与数据支撑。1试验准备1.1样品制备基材选用E32钢,尺寸为6 6 mm37mm6mm。熔覆粉末为粒度在6 0 um左右球形AICrFeMnNi高熵合金粉末,其形貌、成分和结构如图1所示。5000mo0um(a)Powder morphologyElementat.%Fe20.2Cr21.1A117.1Mn20.7MnNi20.9CrCrFeCrMnA1MnNiNi0246810Energy/kev(b)Powdercomp
24、osition(110)*BCC(211)(200)(220)(310)102040608010012020/()(c)Powderstructure图1AICrFeMnNi高焰合金粉末相关信息Fig.1Information about alcrfemnni highentropyalloypowder熔覆前对E32钢板进行除锈、去油处理,试验采用自制改造的等离子熔覆设备,熔覆电流为133A,送粉量17 g/min,转移弧电压40 V,摆动幅度为9mm,摆频为53次/min,送粉气和保护气为氩气。1.2结构表征及性能测试熔覆结束后用线切割工作台将样品按表征要求进行切割截取金相试样,对试样截面
25、采用砂纸打磨抛光,配置王水腐蚀截面5s左右,之后用无水乙醇清洗,在LeicaDMC4500倒置金相显微镜观察涂层金相组织。利用X射线衍射仪(D/max.2400),扫描角度为2 0=512 0、扫描速度5()/min,扫描电镜(ZEI SSEVO 18),能谱仪(ZEISSULTRA55)对熔覆层相组成、微观组织、元素分布进行分析。使用HXD-1000数字式显微硬度计进行显微硬度测试,从涂层表面到基体,每隔0.2 mm取57个点进行测试,加载载荷50 0 g,持续时间10 s。在Gamry-Interface1010E电化学工作站上对样品进行Tafel、EI S测试,测试溶液为3.5wt.%N
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