Ageing hardening and corrosion resistance of Fe60Cr18Cu3(MnCoNiMoAlTi)19 medium-entropy alloy

Artikel i vetenskaplig tidskrift, 2023

Fe60Cr18Cu3(CoMnMoNiAlTi)19 medium-entropy stainless alloy (MEA) was prepared by vacuum arc furnace melting. The ageing hardening mechanism and corrosion resistance of alloy were studied. The results show that the MEA has simple BCC solid solution phase after solidification, due to the influence of medium-entropy effect. HRTEM results show that the high level of lattice distortion in the supersaturated BCC solid solution matrix leads to a high amount of nanometer-sized ordered B2 coherent precipitates after ageing treatment, and the maximum hardness of MESS after ageing reaches 621HV0.5. The resistance to corrosion in hot sulfuric acid and to pitting in the NaCl solution are both greatly improved compared with the conventional 17-4PH steel, as evidenced by more stable anodic passivation zone and significantly reduced corrosion dissolution rate in the MEA. XPS analyses results show that the multi-component passive film, which composes of high contents of anti-corrosion elements including Crhy3 +, Crox3 +, Cu+ox, Ti4ox+, Al3ox+ and Mo6ox+, is the main reason for the excellent pitting resistance and the reduced growth of pitting pit in the NaCl solution.