Relationship between interfacial stress and thermal expansion coefficient of copper–matrix composites with different reinforced phases

Abstract

Copper–matrix composites reinforced with Al₂O₃, SiO₂, SiC and MgO nanoparticles were fabricated using powder metallurgy. The effects of the different nanoparticles on the thermal expansion behaviour of the composites were examined. The thermal expansion properties of the composites were evaluated using the coefficient of thermal expansion from 50 to 500°C. The relationship between interface stress and coefficient of thermal expansion of the copper–matrix composites with various reinforced phases was determined using theoretical models and experimental data. The results show that introducing dispersed nanoparticles into the copper matrix can significantly reduce the coefficient of thermal expansion. By contrast, increasing the temperature increases the thermal expansion coefficient of the copper–matrix composites and the interfacial pressure between the reinforcements and the copper matrix. The calculated pressure values at the nanoparticle–copper matrix interface suggest that plastic deformation occurred in the temperature range from 200 to 250°C for the SiO₂/Cu and SiC/Cu composites and at 350°C for the MgO/Cu and Al₂O₃/Cu composites. These values are consistent with the variations observed in the measured coefficient of thermal expansion.

Keywords:

• Interfacial stress
• Thermal expansion
• Copper matrix
• Plastic deformation

The authors would like to acknowledge the National Natural Science Foundation of China (grant no. 51075122), the State Key Program of National Natural Science of China (grant no. U1034002), Henan Science and Technology Innovation Fund for Outstanding Talents (No.134200510011) and The Combination project of Ministry of Education of Guangdong Province (No. 2012B091100038).