Primary Solidification of T2

The T2 (Mo5SiB2) phase can form as a binary phase that extends into the ternary field or as a new ternary compound. This phase is important for Mo-based alloys due to the excellent oxidation resistance and high thermal stability. Properly reproducing its primary solidification region is essential to accurate prediction of as-cast microstructure for Mo-based alloys. Three calculation examples for the liquidus projection are shown below.

B-Cr-Si

Calculated B-Cr-Si liquidus projection on the Cr rich corner compared with experimental data

Figure 1: Calculated B-Cr-Si liquidus projection on the Cr rich corner compared with experimental data from [2019Cha].

B-Nb-Si

Calculated B-Nb-Si liquidus projection on the Nb rich corner compared with experimental data

Figure 2: Calculated B-Nb-Si liquidus projection on the Nb rich corner compared with experimental data from [2001Can, 2003Jun].

B-Si-V

Calculated B-Si-V liquidus projection on the V rich corner compared with experimental data

Figure 3: Calculated B-Si-V liquidus projection on the V rich corner compared with experimental data from [2017Pin].

References

[2001Can] K. C. G. Candioto, C. A. Nunes, G. C. Coelho, P. A. Suzuki, Microstructural characterization of Nb–B–Si alloys with composition in the Nb−Nb5Si2B (T2-phase) vertical section. Mater. Charact. 47, 241–245 (2001).

[2003Jun] D. M. P. Júnior, C. A. Nunes, G. C. Coelho, F. Ferreira, Liquidus projection of the Nb–Si–B system in the Nb-rich region. Intermetallics 11, 251–255 (2003).

[2017Pin] A. A. A. Pinto da Silva, N. Chaia, F. Ferreira, G. Carvalho Coelho, J.-M. Fiorani, N. David, M. Vilasi, C. A. Nunes, Thermodynamic modeling of the V-Si-B system. Calphad 59, 199–206 (2017).

[2019Cha] V.M. Chad, N. Chaia, T.F. Villela, et al. Experimental determination of liquidus projection in the Cr rich region of the Cr-Si-B system. Journal of Alloys and Compounds 772, 735-739 (2019).