Thermal expansion behavior of nitrogen-processed Al6061/SiC composites

Developing of lightweight materials with extremely low thermal expansion is crucial across various sectors. While Invar exhibits a coefficient of thermal expansion (CTE) below 3 × 10⁻⁶ °C⁻¹, its heavy nature limits its applicability in electric vehicles and aerospace fields. The present study introduces Al6061/SiC composites produced by the nitrogen-induced self-forming aluminum composite (NISFAC) process, wherein CTE is successfully tailored down to an unprecedented value of 2.12 × 10⁻⁶ °C⁻¹ at 100 °C by changing the volume fraction of SiC from 0 to 65%. In-situ AlN, formed at the interface between Al6061 and SiC particles during the NISFAC process, plays a crucial role in minimizing the thermal expansion of the composites by improving crystallographic match and adhesion between SiC particles and the Al matrix.