Study on the process and microstructure of Fe34Mn13.5Al3Cr7.5Ni alloy prepared by spark plasma sintering based on elemental powder

FeMnAlCrNi shape memory alloy exhibits constant superelasticity over a broad temperature range, which has application prospect in aerospace field. In this paper, Fe34Mn13.5Al3Cr7.5Ni superelastic alloy was prepared by spark plasma sintering, and the effects of presintering and sintering process parameters, element diffusion process, and superelastic properties of the alloy were investigated. The orthogonal experiment was conducted to determine the optimal parameters and laws revealed that the compactness degree and hardness of this sintered alloy reached 99.7 % and 291HV, respectively, which were treated by a process of 620 degrees C and 15 min presintering temperature and time, and final sintering temperature of 1000 degrees C under the sintering pressure 45 MPa. In FeMnAlCrNi alloy with multiple elements and significant differences in their melting points, Al element with low melting point will affect the diffusion and microstructure of alloy elements during sintering. The results show that Al element was in a liquid state during the sintering process, which helps to improve the density of the alloy. The remaining Al element in the alloy generated a small amount of pores due to the Kirkendall effect during heat treatment. After heat treatment, the superelastic recovery of the alloy was 0.46 % under 3 % compression.