Table of Contents
Journal of Metallurgy
Volume 2014, Article ID 587265, 8 pages
http://dx.doi.org/10.1155/2014/587265
Research Article

Microstructure and Microhardness Evolutions of High Fe Containing Near-Eutectic Al-Si Rapidly Solidified Alloy

1Physics Department, Faculty of Science, Taif University, P.O. Box 888, Taif 21974, Saudi Arabia
2Solid State Physics Department, National Research Center, Dokki, Giza 12311, Egypt

Received 30 November 2013; Accepted 4 March 2014; Published 25 May 2014

Academic Editor: Gerhard Sauthoff

Copyright © 2014 Emad M. Ahmed and M. R. Ebrahim. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Al-11 wt.% Si-11 wt.% Fe (11.29 at.% Si-5.6 at.% Fe) melt was rapidly solidified into ribbons and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and microhardness technique. The Rietveld X-ray diffraction analysis was applied successfully to analyze microstructure and phase precipitations. On the basis of the aluminum peak shifts measured in the XRD scans, a solid solubility extension value of 1 at.% Si in -Al was determined. SEM investigations confirmed presence of a spherical shape -phase particles in addition to needle and spherical shape -phase particles with contents of 1.1 wt.% and 10.1 wt.% as deduced by XRD analysis. During prolonged annealing process at 350°C/25 h, -phase disappeared, -phase content increased to 30 wt.%, and Si presence becomes more evident as deduced by XRD analysis. EDS analysis confirmed that these particles observed in the as-melt spun alloy are of lower Fe content comparing to those usually observed in the as-cast counter-part alloy. Besides, the length distribution of needle shape -particles has been shortened to be diverse from 1 to 5 μm. The as-melt spun ribbons exhibited enhancement of hardness to 277 HV and further increased during heat treatment (150°C/12 h) to 450 HV. This improvement of microstructure and hardness are the influence of microstructural refinement and modification obtained during the rapid solidification process.