Synthesis and characterization of soft-magnetic (Fe0.7Co0.3)75B21Ta4 metallic glasses by annealing and cryogenic treatment

In order to meet complex service environment, it is necessary to develop soft-magnetic metallic glasses (MGs) with excellent comprehensive performance. The soft-magnetic properties of (Fe _0.7Co _0.3) ₇₅B ₂₁Ta ₄ MGs are improved by appropriate annealing and cryogenic treatment (CT). The coercivity of cryo-treated and 700 K-annealed MGs is less than that of the as-spun one. The 253 K cryo-treated (139.95 emu/ g) and 800 K-annealed (141.63 emu/ g ) ribbons reveal larger saturation magnetization, about 92% higher than the as-spun state. Moreover, the annealing and CT are beneficial to improve the efficiency of reaching magnetic saturation, and propitious to enhance the thermal stability and pitting resistance. Although possessing thicker passive film of the as-spun ribbon, an obvious gap between the film and inner surface damages the sustainable protection of inner surface. The better pitting resistance of the annealed sample at 830 K could be rationalized by the emergence of (Fe,Co,Ta) ₂₃B ₆.