Eur. Phys. J. Plus (2014) 129: 60
https://doi.org/10.1140/epjp/i2014-14060-0

Regular Article

Microstructure and microhardness evolution of melt-spun Al-Si-Cu alloy

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

^* e-mail: makboul67@yahoo.com

Received: 25 November 2013
Revised: 15 February 2014
Accepted: 4 March 2014
Published online: 21 April 2014

Abstract

Al-11 wt.% Si-11 wt.% Cu (11.29 at.% Si-5.1 at.% Cu) 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 the microstructure and phase precipitations. The high cooling rate obtained in rapid solidification has a significant influence on the microstructure and microhardness of this alloy. On the basis of the Al peaks shift measured in the XRD scans, a solid solubility extension value of 3.95 at.% Si and 3.54 at.% Cu in α-Al were determined. No XRD peaks of the Si phase have been detected. XRD peaks of the intermetallic Al₂Cu phase have been observed clearly with estimated content of 12.6 wt.%. During prolonged annealing process at 350°C/25 h, XRD peaks of the Si phase clearly appeared with estimated content of 8.6 wt.% and, moreover, the Al₂Cu phase content increased to 16 wt.%. The estimated crystallite size and micro-strain % of α-Al are 30 nm and 0.056, respectively. The melt-spun wheel side ribbon represents ultra-fine microstructure with particles size less than 1μm and exhibits enhancement of hardness to 241 HV. Hardness has further increased to 291 HV during heat treatment (150°C/12 h). Rapid solidification exhibited a great influence on microstructure and microhardness of the Al-Si-Cu alloy.