Growth Morphology of CuMg2 in Laser Forming of AlCoCrCuFeNi Coating on Mg

Abstract

Abstract-The AlCoCrCuFeNi high-entropy alloy coating was fabricated on pure magnesium by means of laser cladding using a direct blown powder method. The formed coating is composed of two different layers, i.e., a lower composite layer consisting of some partially melted HEA particles in a mixture of Mg and a top HEA coating. Also, some Cu was rejected into the substrate melt during the processing, resulting in the formation of CuMg 2 dendrites. Moreover, the dendritic structure of the CuMg 2 phase, which shows a faceted interface at low growth rates, is shown to undergo a transition from a faceted to non-faceted interface at relatively higher growth velocities. The change in solidification behavior of the formed CuMg 2 phase is likely to be due to the undercooling increase resulting from the solidification velocity increasing.

An Introduction on the Laser Cladding Coatings on Magnesium Alloys

“…However, there are just few studies and few used alloys. AlCoCrCuFeNi coatings on pure magnesium have been investigated by Yue et al [36] and Meng et al [37][38][39]. In the two cases, there is a dilution between the coating and the substrate, thus, some CuMg 2 dendrites were detected.…”

Wear and Corrosion Resistance of Al0.5CoCrCuFeNi High-Entropy Alloy Coating Deposited on AZ91D Magnesium Alloy by Laser Cladding

“…So far, many methods such as arc melting [ 8 ], Tungsten Inert Gas Arc Welding (TIG) [ 9 ], Gas Tungsten Arc Welding (GTAW) [ 10 ], mechanical alloying [ 11 ], DC sputtering [ 12 ], thermal spay technology [ 13 ], and laser cladding [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ] have been adopted to prepare different high-entropy alloys or coatings. Among them, the laser cladding method has attracted special attention because of its advantages of rapid heating, rapid cooling, compact coating, and low dilution rate, etc.…”

“…At present, the preparation of high-entropy alloy coatings by laser cladding mainly focuses on the microstructure and properties of different matrix materials such as Ti-6Al-4V [ 14 , 15 ], carbon steel [ 16 , 17 , 18 , 19 , 20 , 21 ], stainless steel [ 22 , 23 , 24 ], tool steel [ 25 ], die steel [ 26 ], aluminum [ 27 ], magnesium [ 28 , 29 , 30 ], and magnesium alloys [ 31 , 32 ], and different high-entropy coatings [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. It should be noted that the study of the preparation of high-entropy alloy coatings on magnesium and magnesium alloys by laser cladding was mainly carried out by a few researchers: Yue [ 28 , 29 , 31 ], Huang [ 32 ], and Meng [ 30 ]. The possible reason for this is that good-quality laser-clad coatings on magnesium and its alloys are very difficult to obtain because of its low melting point (922K) and low boiling point (1363K).…”