Effect of Nb Content on Microstructure and Properties of Fe–20Mn Alloy Prepared by Ball Milling and Spark Plasma Sintering

In this paper, Fe–20Mn–xNb alloys were prepared by ball milling and spark plasma sintering techniques. Phase constituents were characterized by X-ray diffractometer and Microstructure were characterized by scanning electron microscopy, and the tensile properties, hardness, compactness and damping properties were tested as well. The results show that after ball milling, the metal powders of Fe–20Mn–3Nb first exhibited an irregular plate-like or flake-like morphology, then large irregular particles were broken into fine particles. The addition of Nb element significantly increases the content of γ and ε phase, promoting the formation of γ and ε, and Fe2(Nb, Mn) phase precipitates in Fe–20Mn–3Nb alloy. And mechanical properties of the alloy are significantly improved by adding Nb element. The UTS and YS of Fe–20Mn–3Nb alloy are the highest, which are 818 MPa and 628.7 Mpa respectively, while the elongation of Fe–20Mn–0.5Nb alloy is the highest, which is 31.7% (20.2% higher than that of 0Nb alloy). The hardness and density of the alloy can be increased by adding Nb. The fracture mechanism of Fe–20Mn–xNb (x = 0.5, 1.5, 3) alloys is typical ductile fracture, while the fracture mechanism of Fe–20Mn alloy is quasi-xcleavage fracture. The damping property of Fe–20Mn alloys increases with increasing strain. The addition of Nb can significantly improve the damping properties of Fe–Mn alloys.