Transformation behaviour of the metastable phases in rapidly solidified Pd-Ge alloys

Abstract

Rapid solidification from the melt by a melt-spinning technique is reported for Pd_xGe_1-x (0.75≤ x ≤ 0.85) alloys. The structure and transformation behaviour of the metastable phases so formed are investigated using X-ray diffraction, electron microscopy, differential thermal analysis and resistivity measurements. A glassy phase is observed in the alloys with Ge concentrations of 20% and 22.5%. This structure transforms to the equilibrium phases through a single-step process with an activation energy of 2.7 eV. In alloys with a lower Ge concentration, the as-quenched structure is a mixture of b c c (a=0.3077 nm) and hexagonal (a=0.7460 nm and c=1.2403 nm) phases.