Thermal expansion behavior of Al–B4C composites by powder metallurgy.

In the present investigation, Al/B 4 C 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 B 4 C 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% B 4 C 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. • Hot press method resulted in near theoretical density Al/B 4 C composites. • Hardness of the samples improved with enhancing the reinforcement volume fraction. • CTE of the composite samples non-linearly varied with temperature elevation. • Al/25%B 4 C had the lowest CTE, which is recommended for thermal applications. • Thermoelastic models well-predicted the thermal behavior of the experimental data. [ABSTRACT FROM AUTHOR]