Effects Of Plastic Deformation On The Microstructure And Properties Of Al_0.5 FeCoCrNi High-entropy Alloys

High-entropy alloys have unique components, structure and properties. Currently the related research on the plastic deformation of high-entropy alloys is relatively less. In this work, Alo.sFeCoCrNi high-entropy alloys for super plastic deformation capacity, prepared by vacuum arc melting, were synchronously cold-rolled to the reduction of 30%,60%, and 90%, respectively. The effects of plastic deformation and annealing treatments on microstructure, hardness, corrosion and wear properties of the alloys were investigated, using optical metallographic, X-ray diffraction, scanning electron microscope equipped with an energy dispersive spectrometer, transmission electron microscopy, vichers hardness test, electrochemical workstation, reciprocating friction test machine, and DSC/TGA thermal analyzer. The results demonstrated as follows:Alo.sFeCoCrNi high-entropy alloys have strong work hardening ability. The structure of Al0.5FeCoCrNi high-entropy alloys is face center cubic (FCC) befor and after plastic deformation. The plastic deformation Al0.5FeCoCrNi high-entropy alloys dendrites are flattened and elongated, while the interdendrites are stretched along the rolling direction.The resistance to corrosion of the plastic deformation Al0.5FeCoCrNi high-entropy alloy in the 3.5 wt.% NaC1 solutions is bad; the surface corrosion of pits obviously forms on the alloys. The passivating film of Al0.5FeCoCrNi high-entropy alloys formed in 10wt.%NaOH solution. No obvious corrosion phenomenon occurs in the alloys surface. The resistance to corrosion reduces as the amount of plastic deformation of the alloys increases, as the rolling deformation increases from 0 to 90%.The wear resistance of the Al0.5FeCoCrNi high-entropy alloys decreases as the amount of plastic deformation of the alloys increases. When the alloys are performed under the load of ION and 20N, the wear mechanisms of the alloys poses abrasive wear and adhesive wear. When the alloys rolled with 0 and 30% deformation, are performed under the load of 30N, the wear resistance of the alloys decreases as the amount of rolling deformation of the alloys increases, while the wear resistance of the alloys increases as the amount of rolling deformation of the alloys increases (60～90%), and the wear mechanisms of the alloys is oxidation wear, abrasive wear and adhesive wear.The structure of Al0.5FeCoCrNi high-entropy alloys, rolled deformation with 0,30%,60%, and 90% reductions, transform from single FCC to duplex FCC+BCC after annealing at different temperature (600℃-1140℃). The optical metallographic microstructure of 0-60% plastic deformation alloys are barely changed after annealing at 600℃, there are particle phases precipitation in the 90% plastic deformation alloys annealing at 600℃; dispersion phase precipitation are observed and a small number re-solution of interdendrite take place, when the annealing temperature is at 800℃; as the annealing temperature is at 1140℃, many Al-(Ni, Co, Fe and Cr) phases are observed, which are needle-shaped on dendrite, while the amount of Al-(Ni, Co, Fe and Cr) phases and interdendrite decrease as the annealing time and the amount of plastic deformation of alloys increase. The alloys without plastic deformation appear age hardening effect, while the hardening ability decreases and anneal softening increases as the amount of plastic deformation, annealing temperature and annealing time increase. The alloys, rolled deformation with 60% reductions, appear anneal softening at temperature of 1140℃. Meanwhile, the alloys, rolled deformation with 90% reductions, aslo appear anneal softening at high temperature (800℃-1140℃).