Investigating the effect of hot -rolling and cold -rolling on the microstructure and mechanical properties of high entropy alloy AlCoCrFeNi2.1

: Eutectic high-entropy alloys (EHEAs) exhibit better mechanical and physical behavior compared to conventional alloys. In this study, the eutectic high-entropy alloy AlCoCeFeNi2.1 was prepared by arc melting process. Then, a hot -rolling process was performed on it, and then the thickness was reduced to 90% of the initial thickness through an intense cold -rolling process. The results obtained from the microstructural examination showed that the alloy contains two completely different phases, L12 and B2, The microstructure of the alloy in the as-cast condition consists of dendrites and eutectic layers, by performing the hot -rolling process, the microstructure of the alloy changes and the dendritic arms become fragmented and dispersed in the field. After severe cold -rolling on the alloy, a large portion of the eutectic structure is destroyed and the dendrites are elongated in the direction of rolling. Microhardness results showed that the cold -rolling sample had a hardness of 459 Vickers, which is a significant increase compared to the hot -rolling samples with a hardness of 288 and the as-cast sample with a hardness of 320 Vickers. The shear punch test (STP) results also indicate an increase in the shear strength of the alloy from 276 MPa for the as-cast sample to 390 MPa for the cold -rolling sample. The results of the tensile test at ambient temperature showed that the as-cast sample had an elongation percentage of 19.26% and a strength of 1078 MPa. By cold -rolling the alloy, the strength reached 1956 MPa, but the elongation percentage decreased to 8.8%. The results of XRD analysis also showed that no new phases or intermetallic compounds are formed in the alloy during the hot -rolling and cold -rolling processes.