Microstructural evolutions in the solidification and subsequent diffusion annealing treatment of Mo–12Si–8.5B alloys were studied by using X-ray diffraction, scanning electron microscopy, scanning electron microscopy and transmission electron microscopy. Because the annealing temperature (1900C) was in the vicinity of four-phase equilibrium eutectic reaction (1950C) point of L = Mo3Si + Mo5SiB2 (T2)+Moss (Mo solid solution), the dendrites and lamellar phase have almost been dissolved. Dislocations, Moss precipitates and sub-grain boundary were observed in the T2 phase while the other phases were not found. In addition, dislocations were from excess vacancy during the annealing treatment and play important roles for the Moss precipitate. The dislocations could serve as the heterogeneous nucleation sites and compose of sub-boundary which refines the grain size to some extent. The results observed in this study could be used as a reference for future work on the relationships between microstructure and mechanical property of the Mo–Si–B alloys.

Microstructural Characterization of Mo–12Si–8.5B Alloy Subjected to Diffusion Annealing Treatment. S.P.Yang, H.Kou, G.J.Zhang, G.Liu, F.Jiang, J.Sun: International Journal of Refractory Metals and Hard Materials, 2010, 28[3], 377-82