Thermal expansion behavior of Al-B4C composites by powder metallurgy

In the present investigation, Al/B4C composite samples were prepared by hot press method. Thermal properties of the samples containing different reinforcement contents were evaluated. XRD characterization did not reveal the presence of any detrimental phase. Density and microhardness measurements confirmed proper compaction and high hardness of the samples, respectively. SEM observations showed no evidence of cracks at the matrix/reinforcement interface and it was seen that B4C particles had high wettability with Al matrix. Dilatometry tests demonstrated that by improving the reinforcement content, the coefficient of thermal expansion declined in a way that Al/25% B4C sample had the lowest thermal expansion coefficient (8 ppm/C), which makes it suitable for heat sink applications. Moreover, the experimental results were in good agreement with thermoelastic models in specific temperature ranges. (C) 2019 Elsevier B.V. All rights reserved.