Effect of Thermal Exposure on the Thermal Expansion Behavior of SiCf/Ti-6Al-4V Composite

SiCf/Ti-6Al-4V composites were used to study the effects of thermal exposure on the thermal expansion behavior of composites. The expansion behaviors of the matrix alloy, as-processed composite, and composites exposed at 900 °C for 10, 25 and 75 h were investigated by coefficients of thermal expansion (CTE) test. The results indicate both in longitudinal and transverse direction, the CTE of the exposed composite is higher than that of the as-processed composite. The CTEs of the specimens exposed at 900 °C for 10 and 75 h are higher than that of the specimen exposed at 900 °C for 25 h, no matter in longitudinal or transverse direction. It can be attributed to that there is an appropriate interfacial reaction for the composite exposed at 900 °C for 25 h. Because the prediction of Schapery's model for CTE of composite includes the influence of thermal tensile residual stress in matrix at the whole heating process, the CTE results predicted by Schapery's model are lower than the real CTE obtained from experiments at the high temperature stage of the CTE curve.