Realizing ultrahigh thermal conductivity in bimodal-diamond/Al composites via interface engineering

Bulk materials with high thermal conductivity are fundamentally important to heat dissipation of high-power devices. In this study, a record high thermal conductivity of 1021 ± 34 W m⁻¹ K⁻¹ is achieved in the diamond/Al composites reinforced with bimodal diamond particles. Meanwhile, a coefficient of thermal expansion (CTE) of 3.40 ± 0.10 × 10⁻⁶ K⁻¹ is achieved that is compatible with the semiconductors applied in the high-power devices (∼13.7% and ∼3.7% lower than CTE of a-GaN and c-GaN, respectively). The excellent thermal transport property stems from the increased heat transport channels and well-bonded diamond/Al interfaces. Importantly, the thermal conductivity can also be retained as high as 557 ± 17 W m⁻¹ K⁻¹ at 673 K in the diamond/Al composites, which could greatly widen their applications at high temperatures. This study indicates that concurrently achieving high interfacial thermal conductance, high diamond content, large diamond particle size, and high relative density is the essential way to realize ultrahigh thermal conductivity and diamond/Al composites are promising thermal management materials.