EFFECT OF INTERPHASE, THERMAL INDUCED DISLOCATIONS AND PRESENCE OF VOIDS ON THE FLOW STRESS OF METAL MATRIX NANOCOMPOSITES

Abstract

Interphase, thermal induced dislocations and presence of voids alter the mechanical properties of metal matrix composites (MMCs) but the extent of their effects in MMNCs are not well understood and are investigated using two-dimensional discrete dislocation simulations. While load-bearing effect account for the strengthening in MMCs, it underestimates the strengthening in MMNCs due to a significant missing contribution from impediment of dislocation motion by the nanoparticles. The presence of the interphase can increase the flow stresses by about 50% due to the resistance to dislocation motion in the interphase. The newly generated dislocations are also hindered by thermal induced dislocations and form pile-ups. This further accounts for up to 45% increase in flow stress and degree of hardening. The simulations can account for the effect of the voids observed in the experiments and showed that their distributions can lead to 40% differences in flow stress under 2% tensile strain.