Synergistic Effects of Minor Be and Zr Contents on Microstructural and Mechanical Properties of A356 Cast Alloy

The A356 aluminum alloys are largely used for manufacturing structural components in the automotive and aerospace industries due to their superior castability, strength, resistance to corrosion, and high thermal stability. This study explores for the first time the synergistic effects of minor beryllium (Be) and zirconium (Zr) additions to A356 alloys on their microstructure and mechanical properties. The alloys were solution-treated at 530 ± 2 °C and aged using T4 and T61 tempering to examine the influence of aging. The Be and Zr additions yielded significant changes in the morphology of eutectic silicon particles. Mechanical testing showed that the ultimate tensile strength (UTS) and elongation (ε) of naturally aged, T4-treated samples produced without Be and Zr increased by 20% and 47%, respectively, compared to the as-cast condition. Upon addition of Be and Zr, UTS and ε increased by 34% and 87%, reaching 243 MPa and 11% for T61 treated samples, respectively. Samples containing Be and Zr also exhibited a specific strength 10% higher and are 8% more cost-effective. The findings from this study demonstrate that A356 alloys containing minor Be and Zr additions present a promising balance of enhanced mechanical properties suitable for high-performance applications, with the potential to overcome previously reported results in similar alloys.