Effects of Cr-addition and lamellar microstructure on the oxidation behavior of single crystal (Mo0.85Nb0.15)Si2

The oxidation behavior of (Mo0.85Nb0.15)Si2 single crystals and the influence of Cr-addition were studied focusing on its microstructure dependence. Cr-addition to single-phase C40-structured (Mo0.85Nb0.15)Si2 crystal induced the formation of crystalline silica, leading to slightly larger weight gain during the oxidation test at 1200 °C. Furthermore, Cr-addition to C40/C11b duplex-phase (Mo0.85Nb0.15)Si2 crystal with lamellar structure strongly suppressed the internal oxidation of the C11b phase, resulting in excellent oxidation resistance. C40/C11b lamellae-structured crystals showed better oxidation resistance than the C40-structured crystals.

Research highlights▶ Lamellae-structured (Mo0.85Nb0.15)0.97Cr0.03Si2 shows excellent oxidation resistance. ▶ Cr-addition to C40-structured (Mo0.85Nb0.15)Si2 promotes silica crystallization. ▶ Cr-addition to lamellae-structured (Mo0.85Nb0.15)Si2 inhibits silica crystallization. ▶ Cr-addition to lamellae-structured (Mo0.85Nb0.15)Si2 inhibits internal oxidation.