Particle size effects and thermal hysteresis in crystal structure transformations

Abstract

Particle size affects the temperature and enthalpy of phase transformations as well as the magnitude of thermal hysteresis ΔT, which is shown to be approximately equal to (1/C_pβ)ΔV²/V. The variation of ΔT with particle size (0–150 µm) is interpreted in terms of Turnbull's theory of heterogeneous nucleation. The dependence of the enthalpy of transformation on particle size seems to result from the variation of surface area and surface energy with particle size.