The precipitation behavior and mechanical properties of Cu–Ni–Mn–Fe alloy during aging under elevated compression stresses

Abstract

The Cu–Ni–Mn–Fe alloy is prepared to study its precipitation behavior and mechanical properties during aging under elevated compression stresses. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD), hardness and tensile tests are used for this investigation. The results indicate that the stress-aging treatment leads to the formation of fine, equiaxed grains and twins within the matrix of Cu–Ni–Mn–Fe alloy. During the stress-aging, the density of θ-MnNi precipitates initially decreases and then increases. The stress is further increased from 220 to 385 MPa, the vacancy concentration and dislocation density increase rapidly owing to creep deformation, while the strain-induced effect accelerates the precipitation of θ-MnNi. The results show that the tensile strength and hardness of Cu–Ni–Mn–Fe alloy initially decrease and then increase, and the tensile strength and hardness of the Cu–Ni–Mn–Fe alloy are 890 MPa and 274 HB under the compressive stress of 385 MPa, and the elongation remains at 8.72%. It is mainly attributed to the application of compression stresses during aging, which can enhance both the strength and ductility of the alloy.