Study of the origin of coercivity in the semihard permanent magnet alloy, 82Co-12Fe-6Ti

The dependence of coercivity, resistivity and mechanical hardness on aging time and temperature was studied in solution treated and quenched 5 mil thick 82Co-12Fe-6Ti tape and related to changes in microstructure observed using transmission electron microscopy of thin foils. The results indicate that a fine scale periodic array of coherent precipitates is responsible for the increase in coercivity in this alloy in the solution treated, quenched, and aged state. This periodic coherent phase mixture must coarsen appreciably in order to produce a significant increase in coercivity, whereas mechanical hardness is significantly increased by the development of the modulated structure from the onset of precipitation.