Study on aging strengthening and nano precipitates of Cu-Ni-Mn-Fe alloy

Abstract

This paper presents a systematic study of the precipitation strengthening mechanism in polybasic Cu-Ni-Mn-Fe alloy. The effect of aging treatment on the microstructure, morphologies and phase transition of the Cu-Ni-Mn-Fe alloy were analyzed and discussed using scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and differential scanning calorimeter (DSC), respectively. The θ-MnNi precipitates with a size of 50-100 nm, mainly formed during aging, were considered as the source of the aging strengthening. In addition, there is a semi-coherent between the plane (111) of the θ-MnNi precipitates and the plane (200) of the α-Cu matrix. The density of θ-MnNi precipitates increases with the increase of the aging time. The hardness, yield strength and ultimate tensile strength of the aged alloy increase from 127 to 366HB, 217 to 788 MPa, and 433 to 842 MPa, respectively, which is attributed to precipitation strengthening.