Microstructure and Mechanical Properties of Al_{25 − x}Cr_{25 + 0.5x}Fe₂₅Ni_{25 + 0.5x} (x = 19, 17, 15 at%) Multi-Component Alloys

A series of Al_{25 − x}Cr_{25 + 0.5x}Fe₂₅Ni_{25 + 0.5x} (x = 19, 17, 15 at%) multi-component alloys are prepared by arc-melting and rapid solidification of copper molds. The technique of thermal-mechanical processing is further applied to the master alloys to improve their mechanical properties. These alloys consist of face-centered cubic (FCC) and body-centered cubic (BCC) structure. The volume fraction of the BCC phase increases as Al content increase and Cr and Ni contents decrease, accompanied with a microstructural evolution from dendritic structure to lamella-like structure. Due to the increase of volume fraction of BCC phase, the master alloys exhibit an increased strength and a declined ductility as Al content increases. The rapid solidified alloys have more BCC phase compared with the master alloys, which enhances the strength and decreases the ductility. After homogenization, hot-rolling, and annealing at 1000 °C, the Al₈Cr_33.5Fe₂₅Ni_33.5 alloy displays excellent combination of strength (yield strength is ∼635 MPa and fracture strength is ∼1155 MPa) and ductility (tension strain is ∼11%).