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The research for novel hard magnetic materials for high temperature advanced power applications is still an active area of research. The microstructure and magnetic properties in high temperature hard magnetic alloy have been studied against various milling times in high energy ball milling. The average particle size varies from 1 μm to 50 μm for ball milling times of 30–180 minutes while keeping the constant weight of balls to powder ratio. The Samarium loss increases in the form of its oxide (Sm2O3) and results in an additional phase in microstructure. Due to this additional phase at grain boundaries and triple points, and Sm loss results in the formation of a kink in the second quadrant of demagnetizing curve. This kink shifts from second quadrant of demagnetizing curve to first quadrant with the increase of amount of Sm loss and additional phase in microstructure. The thermomagnetic analysis, X-ray diffraction, microstructure, and chemical composition analysis have identified the additional phase probably the 5:19R (Sm,Zr)(CoFeCu) phase. The best shape of the demagnetizing curve has been obtained after 60 min of ball milling time with good loop squareness and improved magnetic properties at room and high temperature.
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