The phase formation behavior during solidification of Mo-Si-B ternary alloys in the Mo-rich compositional portion was experimentally examined with special attention to the Moss-T2 and Mo-Mo 3Si-T2 eutectics. Primary phases observed in this study were in very good agreement with those shown in a liquidus projection thermodynamically calculated by Yang and Chang. A Mo-9.5Si-14.2B (at.%) alloy, which has a composition close to the Moss-T2 eutectic point, had two specific microstructural areas consisting of a superfine Mo ss-T2 eutectic and a fine Moss-Mo 3Si-T2 three-phase eutectic. A Mo-19.1Si-6.5B alloy aimed to the Moss-Mo3Si-T2 eutectic point also had a fine Mo3Si-T2 eutectic and a Moss-Mo 3Si-T2 eutectic. The compositions of the eutectic phases were determined by electron probe micro-analysis calibrated using a multipoint measurement method and details of the solidification pathways in the Mo-rich compositional portion are discussed based on the experimentally obtained results compared with the liquidus projection.
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