Microstructural Evolution of Mo-Si-B Ternary Alloys through Heat Treatment at 1800°C

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First of all, the as-cast microstructures of Mo-rich Mo-Si-B ternary alloys were investigated around the triple junction point of the primary Mo solid solution, Mo5SiB2 and Mo2B in this work, based on the liquidus projections of the Mo-Si-B system which have been reported in earlier studies. Subsequently, their microstructural evolution through heat treatment was investigated. Since Mo2B crystallizes out during solidification into a primary or secondary phase even though the alloy composition lies in the triangle of Mo-Mo5SiB2-Mo3Si in the Mo-Si-B equilibrium phase diagram, the as-cast microstructures include the non-equilibrated Mo2B in wide compositional ranges. However, Mo2B was completely decomposed during heat treatment at 1800 °C for 24 h and this contributed to the development of homogeneous, fine microstructures. On the other hand, since Mo2B was not decomposed perfectly during 24 h of 1600 °C heat treatment, as-cast microstructures largely remained. Therefore, it is realized that the heat treatment at 1800 °C is necessary to obtain well-developed microstructures of Mo-Si-B alloys.

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Edited by:

M. Heilmaier

Pages:

527-532

DOI:

10.4028/www.scientific.net/AMR.278.527

Citation:

K. Yoshimi et al., "Microstructural Evolution of Mo-Si-B Ternary Alloys through Heat Treatment at 1800°C", Advanced Materials Research, Vol. 278, pp. 527-532, 2011

Online since:

July 2011

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