Amorphous Al-Cr alloys by mechanical grinding of rapidly solidified crystalline powders

Abstract

Mechanical grinding (MG) of rapidly solidified crystalline powders has been performed by the use of a conventional ball-mill. It produced amorphous AI-15 and 20at% Cr alloys. Starting powders for MG were prepared from the ribbons by the single roller method and the component of them was mainly icosahedral quasicrystal. This treatment made it possible to produce the amorphous phase by MG even in the alloy system where liquid quenching did not result in the formation of amorphous phase. The amorphous phase obtained in AI-20 at % Cr alloy was stable up to about 820 K at the continuous heating rate of 0.33 K sec⁻¹ and the activation energy for crystallization was about 240 kJ mol⁻¹.