Experimental study of Moss–T2, Moss–Mo3Si–T2, and Mo3Si–T2 eutectic reactions in Mo-rich Mo–Si–B alloys

•Solidification behavior was examined through careful experimental approaches.•This study suggested accurate method for microstructure analysis.•Interesting behavior for microstructure formation was shown.•Compositional data of eutectic phases were suggested.

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–Mo3Si–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 Moss–T2 eutectic and a fine Moss–Mo3Si–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–Mo3Si–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.