Phase Evolution and Properties of Al 2 CrFeNiMo x High-Entropy Alloys Coatings by Laser Cladding
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Wei Wu, Li Jiang, Hui Jiang, Xuemin Pan, Zhiqiang Cao, Dewei Deng, Tongmin Wang, and Tingju Li (Submitted April 23, 2015; in revised form August 15, 2015) A series of Al2CrFeNiMox (x = 0 to 2.0 at.%) high-entropy alloys coatings was synthesized on stainless steel by laser cladding. The effect of Mo content on the microstructures and mechanical properties of Al2CrFeNiMox coatings was studied. The results show that the laser clad layer consists of the cladding zone, bonding zone, and heat-affected zone. The Al2CrFeNiMox coatings are composed of two simple body-center cubic phases and the cladding zone is mainly composed of equiaxed grains. When the content of Mo reaches 2 at.%, a eutectic structure is found in the interdendritic regions. The surface microhardness of the Al2CrFeNiMo2 coating is 678 HV, which is about three times higher than that of the substrate (243 HV). Compared with stainless steel, the wear resistance of the coatings has been improved greatly. The wear mass loss of the Al2CrFeNiMo alloy is 9.8 mg, which is much less than that of the substrate (18.9 mg) and its wear scar width is the lowest among the Al2CrFeNiMox coatings, indicating that the wear resistance of the Al2CrFeNiMo is the best.
Keywords
high-entropy alloy, laser cladding, microstructures, wear resistance
1. Introduction It is generally accepted that alloys are based on one principal element to serve as a matrix, with the addition of various alloying elements to improve their properties, as for steels, aluminum alloys, and magnesium alloys, bulk metallic glasses (BMGs) (Ref 1). However, Yeh et al. broke through the conventional concept of designing alloys and put forward the concept of ‘‘high-entropy alloys’’ (HEAs) in 1995 (Ref 2, 3). Based on this concept, HEAs were defined to contain at least five major elements in equimolar or near equimolar ratios, the concentration of each element can vary between 5 and 35 at.% (Ref 2-4). Previous studies have shown that most high-entropy alloys consist of simple face-center cubic solid solutions or bodycenter cubic (BCC) solid solutions instead of intermetallics or complex phases because of the high-entropy effect (Ref 2, 5). A lot of research work has shown that HEAs possess many promising properties, such as high hardness and strength (Ref 6-8), superior thermal stability (Ref 9), excellent oxidation resistance, high wear and Wei Wu, Li Jiang, Hui Jiang, and Zhiqiang Cao, Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams (Dalian University of Technology), Ministry of Education, Dalian 116024, China; and Xuemin Pan, Dewei Deng, Tongmin Wang, and Tingju Li, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China. Contact e-mail: [email protected].
Journal of Thermal Spray Technology
corrosion resistance (Ref 10-13), ideal magnetic properties, and so on (Ref 14). High-entropy alloys are mainly prepared by arc melting technology or casting. However, conventional techniques often lead to some deficiencies like segregation, blowhol
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