On the lattice parameter of non-random solid solutions

Abstract

Measurement of the lattice parameter during decomposition of a supersaturated solid solution can provide a method for distinguishing pre-precipitation from precipitation in appropriate circumstances. During pre-precipitation the solute atoms still diffract with the solvent atoms and the fundamental X-ray diffraction peaks are identical to those of the random supersaturated solid solution regardless of the manner in which the solute is distributed among the atomic sites. Thus, a difference exists between heterogeneities produced by pre-precipitation (zones) and those produced by precipitation of a second phase (precipitates). This principle is illustrated for a wide range of alloy systems and its applicability is discussed.