Study of Structural, Compression, and Soft Magnetic Properties of Fe65Ni28Mn7 Alloy Prepared by Arc Melting, Mechanical Alloying, and Spark Plasma Sintering

Soft magnetic Fe65Ni28Mn7 (at. %) alloy was successfully synthesized by mechanical alloying and spark plasma sintering (SPS) and, in parallel, the same composition was prepared by arc melting (AM) for comparison. Several SPS conditions were tested. X-ray diffraction and scanning electron microscopy were used to investigate the structure, phase composition, and morphology of the samples. It was found that mechanical alloying produced BCC and FCC supersaturated solid solution after 130 h of milling, with a fine microstructure (i.e., crystallite size of 10 nm). Spark plasma sintering performed at 750 C-degrees and 1000 C-degrees under two pressures of 50 MPa and 75 MPa revealed stable FCC phases. A single FCC phase was observed after the arc melting synthesis. The magnetic properties of milled powders and solids obtained by AM and SPS were investigated. The specimen consolidated by SPS at 1000 C-degrees under the pressure of 50 MPa exhibits soft magnetic behavior (coercivity 0.07 Oe), whereas the mechanically alloyed sample revealed hard magnetic behavior. The specimen consolidated at 750 C-degrees under a pressure of 75 MPa showed a higher compressive strength of 1700 MPa and a Vickers hardness of 425 +/- 18 HV. As a result, sintering at 750 C-degrees/75 MPa can be utilized to enhance the mechanical properties, while those sintered at 1000 C-degrees/50 MPa increase magnetic softness.

Automated summary

Soft magnetic Fe65Ni28Mn7 alloy was synthesized by mechanical alloying and spark plasma sintering, and its properties were compared with those of the same composition prepared by arc melting. The SPS conditions were tested, and the structure, phase composition, and morphology of the samples were investigated using X-ray diffraction and scanning electron microscopy. It was found that SPS and arc melting synthesis produced stable FCC phases, while mechanical alloying resulted in hard magnetic behavior. The mechanically alloyed sample exhibited a fine microstructure and the consolidated SPS sample showed improved mechanical properties and soft magnetic behavior.