A Direct Extension of the Avrami Equation to Describe the Non-isothermal Crystallization of Al-base Alloys

Abstract

A direct extension of the Avrami equation considering the temperature dependence of the frequency factor is applied to describe the crystallization of a series of Al-Mm-Ni-Co amorphous alloys (Mm is a mischmetal). For high Al content, a nanocrystalline microstructure (fcc α-Al embedded in an amorphous matrix) is formed during the first crystallization process. However, for the alloy with 85 at.% of Al, the devitrification process consists of two strongly overlapped stages, which yield the formation of intermetallic metastable phase(s) without the detection of any amorphous residual matrix. Results are compared with those obtained using other kinetic approaches.