HYPEREUTECTIC Al–Si ALLOYS: CHALLENGES, MECHANISMS, AND ADVANCED SOLUTIONS – A COMPREHENSIVE REVIEW

Ali Mohammed Altameemi; Tuty Asma  Abu Bakar; Mohd Ayub Sulung; Mohammed Rasheed; Aqeel  Ahmed Bhutto; Hamidreza Ghandvar

Ali Mohammed Altameemi Mechanical Power Technical Engineering Department, Al-Amarah University College, Maysan, Iraq
Tuty Asma Abu Bakar Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia
Mohd Ayub Sulung Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia
Mohammed Rasheed Production Engineering & Metallurgy College, University of Technology- Iraq, Baghdad 10066, Iraq
Aqeel Ahmed Bhutto Mechanical Engineering Department, MUET SZAB Campus, Khairpur Mirs 66020, Pakistan
Hamidreza Ghandvar Department of Mechanical Engineering, School of Engineering, New Uzbekistan University, Movarounnahr Street 1, Mirzo Ulugbek District, Tashkent, 100000, Uzbekistan

Keywords: Hypereutectic aluminium silicon alloys, common issues, challenges, solutions

Abstract

Hypereutectic Al–Si alloys are widely used in automotive and aerospace applications due to their excellent wear resistance, low thermal expansion, and high strength-to-weight ratio. However, their performance is strongly influenced by microstructural features, particularly the morphology, size, and distribution of silicon phases, which remain critical challenges in achieving optimal mechanical and corrosion properties. This review addresses the existing research gap by providing a comprehensive analysis of microstructural evolution, processing parameters, and performance-enhancement strategies for hypereutectic Al–Si alloys. The review highlights the influence of silicon content, typically above 12.3 wt.%, on solidification behaviour, nucleation, and defect formation, including porosity and cracking. Emphasis is placed on the transformation of eutectic silicon from coarse plate-like or needle-like structures to refined fibrous or spheroidized morphologies through alloying additions and heat treatment processes. These modifications significantly improve mechanical performance, wear resistance, and corrosion behaviour. Furthermore, the role of processing techniques, including casting methods, cooling-rate control, and heat treatment (e.g., T6), is critically discussed in relation to microstructural refinement and property optimisation. The significance of this review lies in integrating findings from previous and recent studies to provide clear insights into microstructure–property relationships and practical guidelines for alloy design and processing. Future research directions are also outlined, focusing on advanced manufacturing techniques, hybrid reinforcement strategies, and computational modelling to further enhance alloy performance. This review serves as a valuable reference for researchers and engineers working on the development of high-performance Al–Si alloys.