Amorphization of Immiscble Cu-Ta Powders Subjected to Mechanical Alloying

Abstract

Amorphous Cu₃₀Ta₇₀ powders were prepared by mechanically alloying pure crystalline copper and tantalum powders. We characterized the reaction products as a function of ball-milling time by X-ray diffraction, neutron diffraction, EXAFS, DSC and Low-Temperature specific heat measurements. The progress of alloying and amorphization with increasing ball-milling time was revealed in all of these observations, even though Cu-Ta system is characterized by a positive heat of mixing. These results were dicussed consistently in terms of thermodynamic considerations.