Variations in magnetic properties of iron--cobalt--vanadium alloys

Variability in the magnetic properties of an iron-cobalt-vanadium alloy wire processed by commercial vendors has been observed. To ascertain the cause of and cure for this variability, a two-part study utilizing microstructural characterization and statistical evaluation of magnetic data was implemented. Results indicate that wire microstructure, and hence magnetic properties, vary both from wire coil to wire coil within a given melt and along the length of a coil of wire. This variation can be attributed to fluctuations in furnace temperature during the 900 to 9500C strand anneal of the wire. A correlation exists for magnetic properties between the strand-annealed and final aged at 6000C conditions such that evaluation of coercivity and remanence in strand-annealed wire may be feasible for detecting incoming, improperly heat-treated coils at inspection