Effect of Interfacial Bonding Strength on Thermal Expansion Behavior of Carbon-Fiber-Reinforced Copper-Matrix Composites

Alloying elements were added to the copper matrix to produce unidirectional carbon-fiber-reinforced copper-matrix composites with different interfacial bonding strengths (IBS). The thermal expansion coefficients of these composites were determined to investigate the influence of the IBS on the thermal expansion behavior at a low temperature range. The results showed that the thermal expansion coefficient (CTE) at low temperatures (elastic region) of the composites was controlled by the IBS. Furthermore, the IBS of the composites was observed to control the thermal stresses in the matrix and, therefore, to affect the temperature of the onset of matrix yielding. However, the relationship between IBS and expansion behavior at a high temperature range (beyond elastic region) for the present carbon-fiber copper composite system cannot be determined because of the influence of matrix strength. Further work is underway to develop a model so as to correlate the IBS with the CTE of the composites under elastic stage, and a suitable composite system is needed to correlate the IBS to the CTE at high temperatures.