Interfacial structure evolution and thermal conductivity of Cu-Zr/diamond composites prepared by gas pressure infiltration

Diamond particles reinforced Zr-alloyed Cu matrix (Cu-xZr/diamond, x = 0.25–1.0 wt%) composites were fabricated by gas pressure infiltration. Scanning transmission electron microscopy (STEM) was used to characterize the interfacial structure of the Cu-Zr/diamond composites. The results show that the nucleation of ZrC particles is an inhomogeneous process on both diamond (111) and (100) surfaces, and the ZrC particles prefer to nucleate at (111) facets on both surfaces. The results also show that the interfacial carbide morphology is dramatically influenced by Zr content in the Cu matrix. With increasing Zr content from 0.25 to 1.0 wt%, the interfacial structure evolves from small-sized and discrete ZrC particles to continuous carbide layer. As a result, the thermal conductivity firstly increases and then decreases, and the maximum value is obtained at an intermediate Zr content of 0.5 wt%. This study clarifies the formation mechanism of ZrC at the interface and depicts the interfacial structure evolution in the Cu-Zr/diamond composites. The influence of interfacial structure evolution on composite thermal conductivity is also demonstrated.