Design of soft magnetic CoSiB metallic glass with low Co contents

Abstract

Based on the topological models of cluster-lines and crystal clusters destabilization, we propose a modified cluster model for designing metallic glasses based on the proposition that distortion of idealized glass-favoring clusters by addition of solute atoms within their solubility limit can enhance glass forming ability. Using the model, two CoSiB metallic glasses of low Co contents (Co63.1B27Si9.9 and Co65B24.4Si10.6) with good mechanical properties are designed. Despite the similar compositions, these two metallic glasses consist of different clusters, and therefore exhibit different magnetic behaviors. Co63.1B27Si9.9 metallic glass, based on the Co7B3 cluster, shows good soft magnetic properties with low coercivity smaller than 0.9 A/m, while Co65B24.4Si10.6 metallic glass, based on the Co8B3 cluster, exhibits paramagnetic behavior. The origin of these magnetic behaviors was discussed in view of the electronic structures of the metallic glasses. The results indicate that the model was valid not only for glass forming ability but also for tuning properties dominated by short-range orders.