Effect of Al content and cold rolling on the microstructure and mechanical properties of Al5Cr12Fe35Mn28Ni20 high-entropy alloy

In the present study, low-cost high-entropy Al(5,10)Cr12Fe35Mn (28,23)Ni20 alloys containing 5 and 10 at. % Al were designed based on the thermodynamic principles. The chemical compositions of the studied high entropy alloys (HEAs) were selected to obtain face centered cubic solid solutions with good cold deformability. The alloys were produced using arc melting and were subsequently subjected to cold rolling to reduce their thickness up to 90%, to study their structure stability and strengthen them. Elemental mapping of the as-cast and deformed structures was conducted using electron microprobe analysis. Subsequently, the mechanical properties of the as-cast and heavily deformed alloys were determined using micro hardness measurements and tensile and compression tests. The microstructure evolution was studied using X-ray diffraction and electron backscatter diffraction. It was observed that the thermodynamic parameters of HEAs could be used to enhance their mechanical properties, and the experimental results were in agreement with those observations. After substituting Mn with Al in Al5Cr12Fe35Mn28Ni20, the yield stress of Al10Cr12Fe35Mn23Ni20 increased by ∼14%. Moreover, the alloy maintained good cold workability and its tensile ductility exceeded 40%. Cold rolling the alloy to 90% increased its yield stress more than four times. Despite the heavy deformation caused by cold rolling (2.3 true strain), deformation twinning was induced in these alloys.