Materials Chemistry and Physics 239 (2020) 121954 Available online 12 August 2019 0254-0584/© 2019 Elsevier B.V. All rights reserved. Role of Sr on microstructure, mechanical properties, wear and corrosion behaviour of an Al–Mg 2 Si–Cu in-situ composite Saeed Farahany a, * , Hamidreza Ghandvar b , Mansour Bozorg c , Azmah Nordin d , Ali Ourdjini e , Esah Hamzah b a Department of Chemical and Materials Engineering, Buein Zahra Technical University, 3451745346, Qazvin, Iran b Department of Materials, Manufacturing and Industrial Engineering, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia (UTM), 81310, Johor Bahru, Malaysia c Faculty of Chemical and Materials Engineering, Shahrood University of Technology, Iran d Malaysia-Japan International Institute of Technology (MJIIT), Universiti Teknologi Malaysia, 54100, Kuala Lumpur, Malaysia e Department of Mechanical Engineering, Faculty of Engineering, University of Ottawa, Ontario, Canada HIGHLIGHTS � Effect of strontium addition on primary and eutectic Mg 2 Si was evaluated. � The most desirable modifcation was achieved with addition of 0.01 wt% Sr. � Modifcation and de-modifcation mechanisms with increase of Sr were proposed. � Tensile, impact, fracture, wear and corrosion properties were studied. A R T I C L E INFO Keywords: Aluminium composite Mg 2 Si Mechanical properties Wear Corrosion ABSTRACT The infuence of Sr additions on the microstructure of primary and eutectic Mg 2 Si phases, wear and corrosion behaviour of Al–Mg 2 Si–Cu in-situ composite was investigated. The results showed that addition of 0.01 wt% Sr modifed the primary Mg 2 Si morphology but exceeding this level of Sr induced a loss of modifcation as the primary phase morphology coarsened again. The Al–Mg 2 Si eutectic phase, on the other hand, still exhibited a refned structure even with higher levels of Sr additions. Thermal analysis results revealed that both modifcation of the primary Mg 2 Si and refnement of the eutectic Mg 2 Si are most likely related to nucleation and growth stages respectively. The results of 0.01 wt% Sr addition showed that the mean size and mean aspect ratio decreased by about 30% and 6% respectively, but the mean density increased by 185% respectively. The highest UTS, El%, impact toughness and hardness were measured at 101.57 MPa, 1.1%, 1.31 J and 81 VHN respectively. Frac- tography of tensile and impact specimens from the Sr-treated composite revealed that Mg 2 Si particles suffered cracking with few decohesion indicating higher ductility. The results of wear testing also showed that composites treated with Sr have higher wear resistance compared with those of without Sr. The highest resistance to wear was observed in the composite containing 0.01 wt %Sr which is likely the result of good dispersion of fne Mg 2 Si particles in the Al matrix. This fne morphology and uniform distribution of Mg 2 Si particles also contributed to better corrosion resistance by reducing the propagation of corrosion pits. 1. Introduction The term “in-situ metal matrix composite” refers to a specifc class of composite materials consisting of a continuous metallic matrix rein- forced with a second phase that is formed in situ during solidifcation. The motivation behind the fabrication and use of in-situ metal matrix composites (MMCs) lies in the fewer production steps and reduction of production cost. Moreover, wetting of the reinforcement by the matrix is improved [1] and matrix/reinforcement interfaces are stable. Al–Mg 2 Si MMCs have the potential to replace the commonly used hyper-eutectic Al–Si alloys. The characteristics of Mg 2 Si reinforcement particles play a major role in carrying a high portion of the stress when the composite * Corresponding author. E-mail address: saeedfarahany@gmail.com (S. Farahany). Contents lists available at ScienceDirect Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys https://doi.org/10.1016/j.matchemphys.2019.121954 Received 1 April 2018; Received in revised form 7 July 2019; Accepted 4 August 2019 brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by Universiti Teknologi Malaysia Institutional Repository