Superheating and supercooling of lead precipitates in aluminum

Abstract

Thermal hysteresis is observed in x-ray-diffraction studies of the melting and solidification of small crystalline precipitates of lead in aluminum. Reproducible superheating as well as supercooling is present in succesive heating sequences demonstrating that they are intrinsic physical phenomena. For lead precipitates of mean size 140 and 270 A\r{}, the width of the hysteresis loop is 88 and 62 K, respectively. These results are discussed in a phenomenological context considering the lack of free surfaces.