MICROSTRUCTURE OF GERMANIUM QUENCHED FROM THE UNDERCOOLED MELT AT HIGH-PRESSURES

The solidification behavior of germanium quenched from the melt at pre ssure of 2-7 GPa is presented. The solidification parameters of specim en were directly measured under high pressure. The microstructure of s pecimen was observed by electron microscopy. From the measured underco oling and average grain size, the interfacial free energy and activati on energy of crystal growth under high pressures were estimated accord ing to classical nucleation theory. Using high resolution transmission electron microscopy (HRTEM), crystals of sizes ranging from 5 to 100 nm surrounded by an amorphous matrix of germanium were found in those samples which quenched from deeply undercooled melt. (C) 1995 American Institute of Physics.