Thermal expansion behavior of Al–xSi alloys fabricated using selective laser melting

Al–Si alloys are lightweight materials and show excellent mechanical and physical properties, making them appealing for automotive and aerospace industries applications. In this study, Al–(12–50 wt.%)Si alloys (nearly eutectic to hyper-eutectic compositions) were fabricated using a laser-based powder bed fusion process (LPBF) or selective laser melting technique (SLM). The microstructural evolution of the SLM Al–Si alloys as a function of increasing Si contents is investigated in detail. Refined Al and Si phases are observed and the mechanism of the refinement is discussed. In addition, the mechanical properties of the Al–Si alloy processed by casting and SLM were compared. Moreover, the influence of Si content and heating time on the coefficient of thermal expansion (CTE) of the alloys are investigated in detail, and their relationship between theoretical models and the experimental CTE values for the Al–Si alloys will be discussed and compared.