AlMnCrCuFeNi MULTICOMPONENT ALLOY WITH SUPERIOR HARDNESS AND CORROSION RESISTANCE

A multi-component AlMnCrCuFeNi high entropy alloy was prepared by vacuum induction melting and characterized. Optical microscopy analysis showed dendritic solidification, the dendrites and interdendrites containing Cr-Fe-rich precipitates embedded in an Al-Ni matrix. Following the SEM analysis it was observed that the dendrite region is constituted of BCC phases whereas the interdendrite region is a FCC phase and that Al and Ni precipitates are present in the dendritic matrix. The precipitates are a solution of the NiAl compound, B2-type BCC with the same lattice constant as the BCC matrix. XRD analysis revealed two BCC structures composed of Cr-rich phase matrix and Al and Ni rich precipitates and a FCC phase. The lattice constants determined by X-ray diffraction are 2.65 angstrom and 2.73 angstrom for BCC structures and 3.22 angstrom for the FCC. The Vickers micro hardness increased significantly with the chemical homogeneity of the alloy, having a maximum value of 4370 MPa for the four times re-melted sample. Corrosion tests carried out in 3.5 wt.% sodium chloride aerated solution indicated that the corrosion rate of the HEA is of a 1.5-2 order of magnitude smaller that 304 stainless steel.