Investigation of wear, corrosion and oxidation characteristics in consolidated and laser remelted high entropy alloys manufactured via powder metallurgy

High entropy alloys have promising wear, oxidation and corrosion properties compared to conventional alloys and superalloys. In the present study, CrCuFeNiAl0.5 and CrCuFeNiAl0.5Si0.5 alloys were prepared using a traditional powder metallurgy process and then, remelted the surfaces via laser. The laser remelting (LR) process gains a denser and more homogeneous surface to alloys. Pressureless consolidated and laser-remelted specimens were subjected to wear, corrosion and oxidation tests. In the wear tests, it was observed that the wear resistance of Si-containing samples was better due to higher hardness. However, the laser remelting process has in most cases increased rather than reduced wear losses. The less volume loss of laser melted samples was attributed to the almost pure Cu in its content. There is a little difference among all samples in electrochemical corrosion measurements. The formation of fragile passivation layer were observed in potantiodynamic polarization curves of CrCuFeNiAl0.5Si0.5 and LR- CrCuFeNiAl0.5Si0.5 alloys. The alloy with the best corrosion resistance is CrCuFeNiAl0.5Si0.5, whose icorr value is 0,936x10-6 A/cm2.After high-temperature oxidation tests, CrCuFeNiAl0.5 alloy exhibited the worst oxidation performance due to not forming a protective oxide layer on the surface while LR enable the protective oxide scale in short oxidation time. The presence of Si in this alloy relatively enhance the oxidation resistance. The best oxidation performance was observed in LR- CrCuFeNiAl0.5Si0.5 due to the formation of a protective Al2O3 layer during the oxidation tests.