Systematic study of the effect of Cr on the microstructure, phase content and hardness of the AlCrxFeCoNi alloys

Microstructure, phase content and hardness of homogenized multicomponent AlCrxFeCoNi (where x = 0, 0.2, 0.5, 1 and 1.8) alloys was studied systematically using light, electron microscopies and microhardness methods. The goal of this research was to understand the effect of Cr on the microstructure and the reason for the variations in mechanical properties, such as hardness, as a function of Cr concentration. Quaternary AlCoFeNi alloy (i.e., x = 0) was found to be single phase B2 (CsCl structure type) with elongated grains. Alloys containing Cr, solidified in dendritic regime. Phase content has also changed. Addition of Cr promoted the formation of the Body Centered Cubic (BCC) phase at the expense of the B2 and coarsened the grains. At x = 1.8, BCC exceeded the B2 phase volume. Furthermore, in the dendrite region, reversion of the microstructure occurred: when 0