Interfacial characteristic and thermal conductivity of Al/diamond composites produced by gas pressure infiltration in a nitrogen atmosphere

As a promising thermal management material, Al matrix reinforced with diamond particles (Al/diamond) composites are reported to possess high thermal conductivity. The hydrolysis of Al₄C₃ in the composites, however, limits their actual applications. This paper investigates the interfacial structure and thermal conductivity of the Al/diamond composites produced by gas pressure infiltration in a nitrogen atmosphere. The results show that the nitrogen gas can react with Al matrix and hinder the formation of Al₄C₃ at the interface. For comparison, the Al/diamond composites were also fabricated in an argon atmosphere, and the infiltrating parameters were varied to detect the effect on the thermal conductivity. With varying gas atmosphere and infiltrating parameter, the thermal conductivity of the composites varies accordingly. The maximum thermal conductivity of 494W/mK was obtained with the nitrogen atmosphere, lower than the maximum value of 564W/mK with the argon atmosphere. The variation of thermal conductivity is explained from three aspects of diamond surface roughening, nitrogen dissolving into diamond, and hindering Al₄C₃ formation. This study offers a practical way to controlling the interfacial reaction of Al₄C₃ in the Al/diamond composites.