Influence of Crystal Lattice Misfit between Precipitate and Matrix Phases on Critical Size of Coherent Precipitates in Metallic Materials

In order to understand the mechanism of increase in precipitation hardening, the critical size and lattice misfit of coherent precipitates in metallic materials were studied using a method newly developed by the author, which might be called “Different Lattice Mesh Overlapping Method”. The relationship among lattice arrangement, overlapping degree, critical size and lattice misfit of coherent precipitates were first made clear by this method. Then, it was shown that the critical size of coherent precipitates was determined by the overlapping area defined at a overlapping degree of 25%. Since the overlapping area with overlapping degree of 25% is calculated as 56/X (lattice misfit ratio %), the present and previous results are concluded by the following formula. Y(critical size/N)≒56/X(lattice misfit ratio/%)