LOW-SYMMETRY METASTABLE PHASES FORMED DURING CRYSTALLIZATION OF THE METALLIC-GLASS PD80SI20

Low-symmetry metastable phases with planar defects of the metallic gla ss Pd80Si20 are observed at the initial stage of crystallization. Sinc e the reciprocal points are stretched into rods in the direction perpe ndicular to the planar defects, when the reciprocal rods intersect the Ewald sphere, electron diffraction patterns with cross-grating bands will be obtained. Geometrically, the indexes of these diffraction spot s can be directly obtained from these diffraction patterns. The struct ure parameters of these low-symmetry phases are analyzed with the aid of high-order Laue zones and Laue spots. The appearance of these metas table phases reveals that the crystallization of the metallic glass Pd 80Si20 is a complicated and composition dependent process, and the lat tice parameters of these metastable phases are affected by the local c omposition.