Magnesium alloy-based hybrid composites with carbon-fiber, SiC_p, and in-situ Mg₂Si reinforcements have been prepared by the squeeze-infiltration technique. The results of the studies done on the measurement of the coefficient of thermal expansion after thermal cycling of these composites show that the thermal cycling initially leads to rapid linear expansion of the composite. However, the expansion becomes stabilized after a few cycles, pointing toward formation of the stable interfaces due to the formation of stable precipitates. The model for the growth kinetics of these precipitates at the interface shows a rapid initial growth of the precipitates with the number of thermal cycles, which becomes saturated after a few thermal cycles. The thermal treatment of the composite lowers the coefficient of linear thermal expansion, which can be explained on the basis of further stabilization of the interfaces after the thermal treatment.