Spall strength of niobium and molybdenum

Abstract

The shock responses of niobium and molybdenum have been investigated as part of a wider program on bcc metals. Previous work has studied shear strength development behind the shock front and related the observed behaviour to known deformation mechanisms. We now turn our attention to the dynamic tensile (spall) response of these materials. Although both metals are bcc in nature, and both are also adjacent to each other in the periodic table, they nevertheless display markedly different behaviors. Niobium has been shown to be highly ductile, with a high spall strength. In contrast, molybdenum is brittle, with a low spall strength that reduces to near zero as stress amplitude increases. Results are discussed in terms of the deformation mechanisms.