Effect of cold rolling on microstructure and mechanical behavior of Fe35Ni35Cr20Mn10 high-entropy alloy

Abstract

The effects of cold rolling on the microstructure evolution and mechanical behavior of Fe35Ni35Cr20Mn10 high-entropy alloys were investigated. The microstructure was characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The mechanical properties were examined using a CMT5105 tensile tester. The prepared alloy exhibited excellent plastic deformation ability during continuous cold rolling, with a reduction rate greater than 95 %. Cold rolling resulted in extensive grain elongation, formation of deformation bands within the grains, and development of crystallographic textures. The evolution of the microstructure was accompanied by dislocation slip, deformation twins, and formation of shear bands during multipass rolling to a thickness strain of 95 % at room temperature. As the rolling reduction increased, the Brass{110}〈112〉 texture and 〈111〉//RD texture further enhanced. Cold rolling led to substantial strengthening of the prepared alloy; as the rolling reduction increased, both strength and hardness gradually increased. When the rolling reduction reached 95 %, its ultimate tensile strength approached 1116 MPa, which is 2.2 times that in the homogenized condition but at the expense of reduced ductility. After severe cold rolling, an increase in dislocation density occurred along with a microstructure consisting of twins and a network of shear bands formed which enhanced hardness, yield strength, and tensile strength.