Thermal expansion of aluminum matrix composites reinforced by carbon nanotubes with in-situ and ex-situ designed interfaces ceramics layers

•Al/CNT composites with an in-situ Al4C3 and ex-situ TiC interface layers were fabricated using powder metallurgy.•Ex-situ TiC layer on the CNT surface acts as a barrier inhibiting the Al4C3 formation.•CNT with ex-situ TiC layer effectively inhibits thermal expansion of the aluminum matrix.•Interface design strategies are promising to reduce the thermal expansion of composites. [Display omitted] In this study we aim at examining the effect of in-situ and ex-situ interfacial ceramic layers at the Al-CNT interface on the thermal expansion coefficient of aluminum matrix composites at different temperatures. For this, two types of bulk composite materials were obtained by a combination of high-energy ball milling and hot pressing methods. These materials were based on the aluminum alloy reinforced with CNT with in-situ Al4C3 and ex-situ TiC interface ceramic layers. It was found that the ex-situ TiC layer on the CNT surface acts as a barrier layer suppressing the in-situ formation of Al4C3 at heating above 375 °C during the solid phase synthesis of the composite. On average, the composites strengthened by CNT with ex-situ TiC layer can be 15% more effective in restraining the thermal expansion of aluminum matrix in the temperature range from 100° to 400°C compared to composites strengthened by CNT with in-situ Al4C3 layer. On the basis of Turner relation, a modified model is proposed for calculating the CTE of composites reinforced with CNT, taking into account the presence of interface ceramic layer. The obtained data indicate that the interface design strategy is promising for the engineering of aluminum matrix composites with improved CTE.