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

Light weight Al 0.2 CrNbTiV 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. Al 0.2 CrNbTiV RHEA coatings almost free of defects in a thickness from ∼150 μm to 450 μm 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 Al 0.2 CrNbTiV 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 Al 0.2 CrNbTiV 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 . • S K criterion of S < 6.5 kJ/g, 3.85 ≤ K ≤ 140 J/mm 2 is proposed to for HSLC to obtain solid solution structured coating in low dilution (<10 %). • HSLC Al0·2CrNbTiV coating has columnar dominant structure. • High dilution coating possesses more unidirectional but coarser grains with decreased hardness and resistance to plastic deformation.