Thermal expansion behaviors of few-layered graphene-reinforced Al matrix composites

The thermal expansion behaviors of few-layered graphene (FLG)/Al composites fabricated via spark plasma sintering and hot extrusion were evaluated. We demonstrated the first example of efficiently reducing the coefficients of thermal expansion (CTEs) of Al composites by incorporating FLG. The CTE of the Al matrix decreased from 26.72 × 10⁻⁶ K⁻¹ to 25.53 × 10⁻⁶ K⁻¹ with incorporating of merely 0.4 vol% of FLG. Due to the detachment of FLG-Al interface at elevated temperatures, the CTEs of the composites were slightly higher than those estimated by theoretical prediction. This result was further confirmed by the presence of hysteresis phenomenon of the cyclic expansion behavior of the FLG/Al composite. Moreover, the FLG exhibited a high constraining efficiency of ∼13, being more effective at lowering the CTEs of Al composites as compared to other traditional fillers. This work could be significant for guiding the design of high-performance graphene/Al composites for thermal management applications.