Behaviors and interactions of strengthening and constraint for ductile Nbss matrix in Nb–Si based alloys

Abstract

The ductile matrix in composites could be strengthened by incorporating brittle inclusions, while the constraint effect for matrix would become more obvious and detrimental to material toughening. The balance between strengthening and toughening was crucial to achieve excellent comprehensive mechanical properties. Upon the basis of microstructure of Nb–Si in situ composites, a unit rectangular cell containing elastic and isotropic Nb5Si3 particles was modeled, the Niobium solid solution (Nbss) matrix according with the Ramberg-Osgood constitutive relation was recognized as elastic-plastic. For Nb–Si based alloys, the effects of volume fractions of Nb5Si3 reinforcements, stress states and interfacial characteristics on the stress-strain field, flow localization and damage evolution were investigated by the finite element method (FEM). Further, the normalized work of rupture (χ) was calculated quantitatively as a function of volume fractions of Nb5Si3 phase as well as yield strength of Nbss matrix. These results would contribute to acquire more fundamental understanding of the strengthening and constraint effects which were exerted by Nb5Si3 reinforcements to ductile Nbss matrix, also an instructive guidance for the optimum design of Nb–Si based alloys.