Microstructure of Laser Re-Melted AlCoCrCuFeNi High Entropy Alloy Coatings Produced by Plasma Spraying

Abstract

An AlCoCrCuFeNi high-entropy alloy (HEA) coating was fabricated on a pure magnesium substrate using a two-step method, involving plasma spray processing and laser re-melting. After laser re-melting, the microporosity present in the as-sprayed coating was eliminated, and a dense surface layer was obtained. The microstructure of the laser-remelted layer exhibits an epitaxial growth of columnar dendrites, which originate from the crystals of the spray coating. The presence of a continuous epitaxial growth of columnar HEA dendrites in the laser re-melted layer was analyzed based on the critical stability condition of a planar interface. The solidification of a columnar dendrite structure of the HEA alloy in the laser-remelted layer was analyzed based on the Kurz-Giovanola-Trivedi model and Hunt's criterion, with modifications for a multi-component alloy.

Application Prospects and Microstructural Features in Laser-Induced Rapidly Solidified High-Entropy Alloys

“…Yue et al 44 modeled the CET process in the AlCoCrCuFeNi HEA coating, based on the Kurz-Giovanola-Trivedi (KGT) model and Hunt's criterion. From the modeling results, the columnar crystal growth was maintained when the volume fraction of equiaxed crystals is below 0.66%.…”

Liquid Phase Separation and the Aging Effect on Mechanical and Electrical Properties of Laser Rapidly Solidified Cu100−xCrx Alloys

“…This increase can be attributed to the lower density and, hence, the floating tendency of the Cr-rich liquid in the laser-melted pool. According to previous descriptions of the melt and the solidification process in the laser-melted pool, the crystal growth velocity (v) depends on the location and is linked to the heat source velocity (i.e., laser feed rate, v s ) [10,11]. The crystal growth velocity, v, will increase rapidly from zero at the bottom of the alloy to a value close to v s at the surface, and is accompanied with a decrease of the time interval (Δt) between the start of liquid separation and solidification.…”

Microstructures and properties of high-entropy alloy films and coatings: a review

“…Up to now, a number of technologies have been applied to fabricate HEA films and coatings, e.g. magnetron sputtering [34][35][36], laser cladding [37,38], spraying [39], electrodeposition [40], plasma-transferred arc cladding [41], and others. The present experimental results have proved that HEA films and coatings can show excellent mechanical and physical properties, such as the high hardness and elastic modulus [42,43], superior wear resistance [44], corrosion [45] and temperature resistance [46], as well as the appealing electrical [47] and magnetic properties [48].…”