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arXiv · 1909.04707

Low temperature deformation of MoSi$_2$ and the effect of Ta, Nb and Al as alloying elements

Carolin Zenk·James S. K. -L. Gibson·Verena Maier-Kiener·Steffen Neumeier·Mathias Göken·Sandra Korte-Kerzel
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Abstract

Molybdenum disilicide (MoSi$_2$) is a very promising material for high temperature structural applications due to its high melting point (2030 {\deg}C), low density, high thermal conductivity and good oxidation resistance. However, MoSi$_2$ has limited ductility below 900 {\deg}C due to its anisotropic plastic deformation behaviour and high critical resolved shear stresses on particular slip systems. Nanoindentation of MoSi$_2$ microalloyed with aluminium, niobium or tantalum showed that all alloying elements cause a decrease in hardness. Analysis of surface slip lines indicated the activation of the additional {1 1 0}<1 1 1> slip system in microalloyed MoSi$_2$, which is not active below 300 {\deg}C in pure MoSi$_2$. This was confirmed by TEM dislocation analysis of the indentation plastic zone. Further micropillar compression experiments comparing pure MoSi$_2$ and the Ta-alloyed sample enabled the determination of the critical resolved shear stresses of individual slip systems even in the most brittle [0 0 1] crystal direction.

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Carolin Zenk, James S. K. -L. Gibson, Verena Maier-Kiener, Steffen Neumeier, Mathias Göken, Sandra Korte-Kerzel. 2019-09-10. Low temperature deformation of MoSi$_2$ and the effect of Ta, Nb and Al as alloying elements. https://arxiv.org/abs/1909.04707

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