Enhanced thermal stability of amorphous Al-Fe alloys by addition of Ce and Mn

Abstract

The thermal stability of mechanically alloyed amorphous Al-Fe-based alloy powders, with nominal compositions Al _82 Fe _16 Ce _2 and Al _82 Fe _14 Mn _2 Ce _2 , was investigated using differential scanning calorimetry (DSC), x-ray diffraction (XRD), and scanning electron microscopy (SEM) complemented by energy-dispersive x-ray spectroscopy (EDX). Analysis through DSC indicated that both Al _82 Fe _16 Ce _2 and Al _82 Fe _14 Mn _2 Ce _2 alloys undergo a two-stage crystallization process. Notably, the initial crystallization temperatures for the Al _82 Fe _16 Ce _2 and Al _82 Fe _14 Mn _2 Ce _2 alloys were determined to be approximately 525 °C and 550 °C, respectively. This high thermal stability is attributed to the delayed nucleation process induced by the presence of Ce and Mn within the Al-Fe matrix. During polymorphic crystallization, distinct phases such as β -AlFe, Al _13 Fe _4 for Al _82 Fe _16 Ce _2 , and β -Al(Fe, Mn), Al _13 Fe _4 , Al _10 CeMn _2 for Al _82 Fe _14 Mn _2 Ce _2 were identified. Furthermore, post-annealing of these amorphous alloy powders at elevated temperatures of 600, 700, and 800 °C led to distinct morphological characteristics based on the alloy composition. For Al _82 Fe _16 Ce _2 , the particles preserved a nearly spherical morphology, with size distributions ranging from 1 to 5 μ m. In contrast, for Al _82 Fe _14 Mn _2 Ce _2 , the particles exhibited an irregular shape with a broader size range of 1 to 15 μ m.

Keywords

• mechanical alloying
• thermal stability
• Al-Fe-based amorphous alloy
• solid-state transformations
• amorphization