Zero Thermal Expansion, High Specific Thermal Conductivity, and Good Machinability of Cu 2P 2O 7/2024al Composite

Negative thermal expansion (NTE) materials can be applied to suppress thermal expansion of other materials, forming composites with zero thermal expansion (ZTE). However, the shortcomings (e.g., high density, narrow working temperature window) inherited from various NTE materials hinder the applications of corresponding ZTE composites. The modified Cu2P2O7 by reducing oxygen deficiencies has a relatively low density and strong NTE over a wide temperature range, which therefore was used to composite with 2024Al. When the volume content of modified Cu2P2O7 is about 50%, the composite Cu2P2O7/2024Al shows ZTE effect, and the linear coefficient of thermal expansion is about -0.014 ppm/K at 273-333 K. The ZTE composite also exhibits a high specific thermal conductivity, significantly superior to other existing ZTE materials. Furthermore, due to the matched moduli between Cu2P2O7 and 2024Al, the ZTE composite displays good machinability. The current ZTE composite may have great potential applications in the fields of high-precision electronics and optics.