Magnetization process in devitrified glassy alloy

Co84Nb10B6 metallic glasses have been devitrified so as to produce a series of specimens with increasingly coarser microstructure. Samples annealed for 1 h at Ta≤700 °C remain largely glassy with a distribution of fine cobalt precipitates. Their coercivities increase with mean precipitate diameter. Samples annealed for 1 h at Ta≥700 °C are fully crystallized (fcc Co plus a Co-Nb boride). Their coercivities decrease with increasing mean grain size. An abrupt increase in coercivity occurs between Ta=650 and 700 °C.