Abstract
Al0.5CoCrCuFeNiSi high entropy alloy coating without and with a 1 wt.% Y2O3 addition was fabricated by laser cladding technique on H13 substrate. The results showed that the laser cladding coatings without and with Y2O3 addition consist of a mixture of body centered cubic (BCC) dendrites and face centered cubic (FCC) interdendrites. With the addition of Y2O3, the peaks of BCC dendrites in the coating shifted to leftwards, which is caused by the distortion of lattice due to the dissolution of Y with larger atomic radius. There exist cracks and porosities in the coating without Y2O3 addition. With Y2O3 addition, the cracks and porosities in the laser cladding coating were inhibited greatly. In addition, the microstructure of the coating with Y2O3 addition was refined due to the improving of the ratio of nucleation. The enhancement of properties, such as hardness, wear resistance and corrosion resistance, of the coating with Y2O3 addition came from the inhibition of cracks and porosities and the refinement of microstructure.
Highlights
In the service of man, wear and corrosion usually initiate from the surface of engineering materials.Modifying the surface of existing materials to enhance their surface properties while not affecting the properties in the sub-surface region is more economical than fabricating the bulk materials
Multi-principal elements give rise to high configurational entropy and the formation of randomized solid solution phases in High entropy alloys (HEAs) instead of complex intermetallic compounds as expected in traditional alloys system [9,10]. Due to their simple solid solution structure, HEAs possess an outstanding combination of strength and ductility and excellent surface properties including hardness, wear resistance, oxidation and corrosion resistance, Crystals 2020, 10, 320; doi:10.3390/cryst10040320
The HEA Al0.5 CoCrCuFeNiSi coatings without and with 1 wt.% Y2 O3 addition were fabricated on the substrate by laser cladding technique using elemental powders of Al, Co, Cr, Cu, Fe, Ni, Si and commercial Y2 O3 powders with purity higher than 99.9%
Summary
In the service of man, wear and corrosion usually initiate from the surface of engineering materials.Modifying the surface of existing materials to enhance their surface properties while not affecting the properties in the sub-surface region is more economical than fabricating the bulk materials. Various surface treatment techniques, such as laser cladding, plasma spraying process, friction stir cladding, physical vapor deposition and chemical vapor deposition, have been developed over the years [1,2,3,4,5] Among these approaches, laser cladding has attracted a high level of interest of the scientific community due to its distinct advantages including faster processing rates, better control of coating thickness, minimal dilution, ease of equipment availability, maintainability and metallurgical substrate/coating bonding [6]. Multi-principal elements give rise to high configurational entropy and the formation of randomized solid solution phases in HEAs instead of complex intermetallic compounds as expected in traditional alloys system [9,10] Due to their simple solid solution structure, HEAs possess an outstanding combination of strength and ductility and excellent surface properties including hardness, wear resistance, oxidation and corrosion resistance, Crystals 2020, 10, 320; doi:10.3390/cryst10040320 www.mdpi.com/journal/crystals
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