Low cost hard magnetic material containing amorphous phase

摘要

A hard magnetic material contains an element T (one or more of iron, cobalt and nickel), an element R (one or more rare earth elements), boron and optionally an element M (one or more of zirconium, niobium, tantalum, hafnium, vanadium, titanium, molybdenum and tungsten) and has a multi-phase structure comprising, as main phases, a T phase with an average grain size of less than 100 nm, a R2Fe14B phase with an average grain size of less than 100 nm and an amorphous phase with an average content of element R or of an element M which is less than that in the R2Fe14B phase and greater than that in the T phase. Also claimed is a hard magnetic material obtained by heat treating an alloy, which includes the above elements T, R and boron and which contains more than 50 vol.% of an amorphous phase, to produce a multi-phase structure containing, as main phases, a T phase with an average grain size of less than 100 nm, a R2Fe14B phase with an average grain size of less than 100 nm and an amorphous phase, the difference between the precipitation temperature of the T phase in the amorphous phase and that of the R2Fe14B phase being less than 500 deg C and each precipitation temperature being in the 500-1000 deg C range.