The role of percolation threshold for the control of the hardness and thermal stability of super- and ultrahard nanocomposites

It is shown that enhancement of the hardness in superhard nanocomposites is due to the percolative nature of phase segregation, which results in approximately I-ML coverage of the transition metal nanocrystals with the non-polar Si3N4. The formation of a nanostructure that is stable against coarsening up to relatively high temperatures is a consequence of the thermodynamically driven segregation of the immiscible phases. (C) 2001 Elsevier Science B.V. All rights reserved.