The effect of the thermomechanical process on microstructure and mechanical properties of (CO25CR15FE20NI40)83AL17 high entropy system

AlCoCrFeNi alloy is one of the multicomponent alloys and they are known as with their important thermomechanical properties such as good combination of ductility and strength. This high entropy alloy system has also durability at high temperatures and good compressive strength. AlCoCrFeNi alloy system has face centered cubic (FCC) and body centered cubic (BCC) in its structure and this multicomponent system provides good ductility and strength combination. In the scope of this study, it was aimed to analyze the effect of mechanical, thermal and thermomechanical processes on the microstructure and hardness of (Co25Cr15Fe20Ni40)83Al17 eutectic high entropy alloy, which was produced by the vacuum arc melting and casting method. Cryorolling, cold rolling (room temperature rolling) and hot rolling (500 C, 750 C and 1000 C) as well as different annealing temperatures (750 C, 1000 C and 1100 C) were applied to the plates. As the result of the cryorolling, maximum 7% deformation can be attained, which was well below the targeted deformation. The applied deformation has increased to 50% and 60 % as the result of cold and hot rolling, respectively. The limited deformability was attributed to the increased BCC/B2 content in the eutectic FCC-BCC phase mixture with the applied deformation according to XRD results. Moreover, it was observed that the ratio of FCC/L12 phase in the eutectic phase mixture was increased by annealing at or above 1000 C. The maximum hardness (412 HV), on the other hand, was attained after 50% cold-rolling while similar hardness value (399 HV) was measured after 53% hot rolling at 750C indicating the dynamic recrystallization did not have a pronounced affect till 1000C.