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<p>Aluminium–silicon (Al–Si) eutectic alloys are the most common materials for automotive and light structural applications due to their good castability and high strength-to-weight ratio. Nevertheless, there are situations where improved mechanical performance is required for more demanding operating conditions. The influence of Silicon Carbide (SiC) reinforcement, Magnesium (Mg) addition and ageing on hardness, tensile behaviour and fracture properties of stir-cast Al–Si eutectic composites was studied in this work. The composites were prepared at 2 and 4 wt% SiC particles and 0.75 and 1.5 wt% Mg additions to enhance wettability and particle–matrix bonding. The materials were tested in the as cast state and after solution treatment at 520&#xa0;°C and artificial ageing at 100&#xa0;°C to peak hardness.</p><p>The result is that mechanical response of the investigated composites is largely influenced by both Mg and SiC amounts. As-cast for the composite with 0.75 wt% Mg and 2 wt% SiC, the hardness was 143 Brinell Hardness Number (BHN) and ultimate tensile strength (UTS) was 162&#xa0;MPa. Further enhancement in both properties was observed with an increase in Mg and SiC content. A hardness of 179 BHN and UTS of 198&#xa0;MPa was achieved for the composite with 1.5 wt% Mg and 4 wt% SiC after peak ageing at 100&#xa0;°C for 4.5&#xa0;h. After ageing, fractography analysis showed that there is transition between a slight ductile debonding fracture in the low-reinforcement composites and a mixed fracture mode with very fine dimples and fractured SiC particles. The enhanced mechanical properties at peak ageing condition are due to the synergetic effect of particle reinforcement, improved interfacial bonding by Mg addition and precipitation hardening during ageing.</p>

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Hardness, tensile and microstructural characteristics of stir cast Al–Si eutectic matrix SiC-reinforced composites in As-cast and peak-aged conditions

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月11日

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  • Ashwin Shetty,
  • Sathyashankara Sharma,
  • Thirumaleshwara Bhat,
  • Ananda Hegde,
  • Gajanan Anne,
  • Ravikantha Prabhu,
  • Rajesh Bhat

摘要

Aluminium–silicon (Al–Si) eutectic alloys are the most common materials for automotive and light structural applications due to their good castability and high strength-to-weight ratio. Nevertheless, there are situations where improved mechanical performance is required for more demanding operating conditions. The influence of Silicon Carbide (SiC) reinforcement, Magnesium (Mg) addition and ageing on hardness, tensile behaviour and fracture properties of stir-cast Al–Si eutectic composites was studied in this work. The composites were prepared at 2 and 4 wt% SiC particles and 0.75 and 1.5 wt% Mg additions to enhance wettability and particle–matrix bonding. The materials were tested in the as cast state and after solution treatment at 520 °C and artificial ageing at 100 °C to peak hardness.

The result is that mechanical response of the investigated composites is largely influenced by both Mg and SiC amounts. As-cast for the composite with 0.75 wt% Mg and 2 wt% SiC, the hardness was 143 Brinell Hardness Number (BHN) and ultimate tensile strength (UTS) was 162 MPa. Further enhancement in both properties was observed with an increase in Mg and SiC content. A hardness of 179 BHN and UTS of 198 MPa was achieved for the composite with 1.5 wt% Mg and 4 wt% SiC after peak ageing at 100 °C for 4.5 h. After ageing, fractography analysis showed that there is transition between a slight ductile debonding fracture in the low-reinforcement composites and a mixed fracture mode with very fine dimples and fractured SiC particles. The enhanced mechanical properties at peak ageing condition are due to the synergetic effect of particle reinforcement, improved interfacial bonding by Mg addition and precipitation hardening during ageing.