| Summary: | Fe-NiAlMn and Fe-CuNiAlMn alloys were aged at 500℃ for different time after solution treatment at 900℃ for 2 h and water quenching. The influence of Cu-addition on the precipitation strengthening in Fe-CuNiAlMn alloy was studied using hardness testing and atom probe tomography(APT). The results show that the addition of Cu effectively enhances the effect of precipitation strengthening in the early stage of aging and accelerates the whole process of precipitation strengthening. Cu elements first segregate to form Cu-rich phase, which promotes Ni, Al and Mn elements to segregate and nucleate at the interface between Cu-rich phase and matrix to form Ni(Al, Mn) phase resulting in core-shell structure during aging. With the extension of aging time, Cu-rich phase changes from BCC to FCC and separates from Ni(Al, Mn) phase.
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