High-Temperature Deformation Behavior of (Mo_0.85Nb_0.15)Si₂ Crystals with C40/C11_b Lamellar Microstructure

Abstract:

The effect of alloying element (such as Cr, Zr, and Ir) addition on the high-temperature creep deformation behavior of C40/C11_b lamellar-structured (Mo_0.85Nb_0.15)Si₂ silicide crystals was examined. The results indicated that these additions all lead to a decrease in the steady-state creep strain rate (SSCR) when the applied stress is parallel to the lamellar interface. To clarify the origin of this, the dependence of the creep deformation behavior on the microstructure was determined in detail. As a result, it was found that the C40 phase acts as a strengthening phase during the deformation of the C40/C11_b duplex-phase crystals. The variant-1-type C11_b phase grains, whose loading orientation is parallel to [001], also acts as an effective strengthening component. The decrease in SSCR by Cr or Zr addition is attributed to the increase in volume fraction of those C40 phase and C11_b-V1 grains. The refinement of microstructure by Ir addition was also found to result in a modest decrease in the SSCR.

• Periodical: Materials Science Forum (Volume 879)
• Pages: 677-683
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.879.677
• Online since: November 2016
• Authors: Koji Hagihara*, Haruka Araki, Takaaki Ikenishi, Takayoshi Nakano
• Keywords: Creep Deformation, High-Temperature Material, Lamellar Microstructure, Silicide

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