Table of Contents Author Guidelines Submit a Manuscript
Advances in Materials Science and Engineering
Volume 2017, Article ID 4712946, 12 pages
https://doi.org/10.1155/2017/4712946
Research Article

Effect of Rare Earth Metals, Sr, and Ti Addition on the Microstructural Characterization of A413.1 Alloy

1Université du Québec à Chicoutimi, Chicoutimi, QC, Canada
2General Motors, Materials Engineering, 823 Joslyn Avenue, Pontiac, MI 48340, USA
3Nemak, S.A., Libramiento Arco Vial Km. 3.8, 66000 Garcia, NL, Mexico

Correspondence should be addressed to F. H. Samuel; ac.caqu@leumashf

Received 5 February 2017; Accepted 9 March 2017; Published 16 May 2017

Academic Editor: Patrice Berthod

Copyright © 2017 M. G. Mahmoud et al. 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

The present work was performed on A413.1 alloy containing 0.2–1.5 wt% rare earth metals (lanthanum or cerium), 0.05–0.15% Ti, and 0–0.02 wt% Sr. These elements were either added individually or combined. Thermal analysis, image analysis, and electron probe microanalysis were the main techniques employed in the present study. The results show that the use of the depression in the eutectic temperature as a function of alloy modification cannot be applied in the case when the alloy is treated with rare earth metals. Increasing the concentration of RE increases the solidification zone especially in Sr-modified alloys leading to poor feeding ability. This observation is more prominent in the case of Ce addition. Depending upon the amount of added Ti, two RE based intermetallics can be formed: (i) a white phase, mainly platelet-like (approximately 2.5 μm thick), that is rich in RE, Si, Cu, and Al and (ii) a second phase made up of mainly grey sludge particles (star-like) branching in different directions. The grey phase is rich in Ti with some RE (almost 20% of that in the white phase) with traces of Si and Cu. There is a strong interaction between RE and Sr leading to a reduction in the efficiency of Sr as a eutectic Si modifier causing particle demodification.