Dynamics of consolidation and crack growth in nanocluster-assembled amorphous silicon nitride

Consolidation and fracture dynamics in nanophase amorphous Si3N4 are investigated using 106-atom molecular-dynamics simulations. At a pressure of 15 GPa and 2000 K, the nanophase system is almost fully consolidated within a fraction of a nanosecond. The consolidation process is well-described by the classical theory of sintering. Under an applied strain the consolidated system develops several cracks which propagate parallel to each other, causing failure at multiple sites. The critical strain at which the nanophase system fractures is much larger than that for crystalline Si3N4.