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In the present study, the laser melting deposition (LMD) technology was adopted to fabricate FeCoCrNiMn and FeCoCrNiMnAl0.75high entropy alloys (HEAs). Then, laser welding method was used to join the HEAs in forms of similar (FeCoCrNiMnAl/FeCoCrNiMnAl and FeCoCrNiMnAl0.75/FeCoCrNiMnAl0.75) and dissimilar (FeCoCrNiMnAl0/FeCoCrNiMnAl0.75) combinations, respectively. Ultra-depth field microscope and electron backscatter diffraction detection were used to observe the macro-morphology and microstructure, respectively. It was found that the width of the weld bead and heat-affected zone with higher aluminium content was larger. In both base metals and welded joints, aluminium promoted the face-centered cubic (FCC) phase transfer into body-centered cubic (BCC), significantly refined the grain and the dislocation density of HEA is also increased, which increased strength and hardness, and decreased ductility.HighlightsThe FeCoCrNiMn/FeCoCrNiMn, FeCoCrNiMn/FeCoCrNiMnAl0.75, FeCoCrNiMnAl0.75/FeCoCrNiMnAl0.75joints were produced by laser welding.The widths of the weld bead and heat-affected zone increased with higher Al content.The weld bead with higher content of Al exhibited higher strength and hardness, but lower ductility.

In the present study, the laser melting deposition (LMD) technology was adopted to fabricate FeCoCrNiMn and FeCoCrNiMnAl0.75high entropy alloys (HEAs). Then, laser welding method was used to join the HEAs in forms of similar (FeCoCrNiMnAl/FeCoCrNiMnAl and FeCoCrNiMnAl0.75/FeCoCrNiMnAl0.75) and dissimilar (FeCoCrNiMnAl0/FeCoCrNiMnAl0.75) combinations, respectively. Ultra-depth field microscope and electron backscatter diffraction detection were used to observe the macro-morphology and microstructure, respectively. It was found that the width of the weld bead and heat-affected zone with higher aluminium content was larger. In both base metals and welded joints, aluminium promoted the face-centered cubic (FCC) phase transfer into body-centered cubic (BCC), significantly refined the grain and the dislocation density of HEA is also increased, which increased strength and hardness, and decreased ductility.HighlightsThe FeCoCrNiMn/FeCoCrNiMn, FeCoCrNiMn/FeCoCrNiMnAl0.75, FeCoCrNiMnAl0.75/FeCoCrNiMnAl0.75joints were produced by laser welding.The widths of the weld bead and heat-affected zone increased with higher Al content.The weld bead with higher content of Al exhibited higher strength and hardness, but lower ductility.

In this study, the (FeMnCrNiCo?+?20%TiC) laser cladding layer was re-treated through multiple-pass in-situ laser remelting. Optical microscopy, scanning electron microscopy, and X-ray diffraction were used to analyse the evolution of microstructures and phases before and after the in-situ laser remelting processes. The micro-hardness and wear resistance of the composite coatings were systematically investigated using micro-hardness and abrasion. Results show that in-situ laser remelting decreased the dilution rate. The thermal effect of laser melting and the Maragni action in the liquid coating metal enabled the large-sized and loosened ceramic particles to remelt into the cladding layers. As a result, the ceramic particles in the cladding layers after in-situ laser remelting were modified considerably in terms of their spherification rate, dimension uniformity, and particle distribution. The weak spots caused by stress on the surfaces of the cladding layers were reduced, and accordingly the wear resistances improved.

In the present study, FeCoCrNiAlx(x?=?0.3, 0.7) coatings were fabricated by laser cladding technology. XRD analysis and scanning electron microscopy (SEM) were used to investigate the evolution of phases and microstructures before and after the high-temperature oxidation test. The micro-hardness, tribological behaviour, and corrosion resistance of the coatings, before and after the high-temperature treatment, were systematically investigated using micro-hardness test, abrasive wear test, and electrochemical corrosion test. The microstructure and properties of FeCoCrNiAl0.3cladding layer changed little before and after the high-temperature oxidation test. The high-temperature condition promoted the generation of BCC solid solutions at the grain boundaries when the Al element content was 14.89% (i.e. 0.7 mol). This enhanced the micro-hardness and tribological behaviour, but deteriorated the corrosion resistance.