Microstructure and properties of lightweight Al0.2CrNbTiV refractory high entropy alloy coating with different dilutions deposited by high speed laser cladding

Light weight Al0.2CrNbTiV refractory high-entropy alloy (RHEA) coatings with different dilutions were deposited by high speed laser cladding technology (HSLC) on TC4 substrate. The effect of key processing parameters on the dilution of HSLC coatings were investigated, and coating with a dilution lower than 3 % could be obtained through the control of specific energy density and specific powder density. Al0.2CrNbTiV RHEA coatings almost free of defects in a thickness from similar to 150 mu m to 450 mu m were manufactured with varying dilution of 2.4 %-33.6 %. HSLC facilitated the formation of disordered solid solution, and S-K criterion of S < 6.5 kJ/g, 3.85 <= K <= 140 J/mm(2) was proposed based on the processing characteristics of HSLC to obtain simple solid solution structured coating in low dilution (< 10 %). The HSLC deposited Al0.2CrNbTiV RHEA coatings in typical dilution of 3.1 % and 31.9 % were analyzed, which kept simple BCC solid solution structure, accompanied by an increase in lattice constant with the massively dissolved Ti elements in high dilution coating. Moreover, the Al0.2CrNbTiV RHEA coatings exhibited columnar dominant structure with fine grain size. The coating in high dilution exhibited a stronger tendency for epitaxial growth with increased grain size and lower dislocation density, resulting in a decrease in hardness as well as the resistance to plastic deformation.

Automated summary

In this study, lightweight refractory high-entropy alloy coatings with different dilutions were deposited on TC4 substrate using high-speed laser cladding technology. By controlling specific processing parameters, coatings with a dilution lower than 3% were successfully obtained, and nearly defect-free coatings were manufactured within a dilution range of 2.4%-33.6%.