Effect of Alumina Fibers on the Aging Characteristics of 2024-Based Metal-Matrix Composites

The age-hardening precipitation reaction in aluminum matrix composites reinforced with discontinuous alumina fibers was studied using the differential scanning calorimetry (DSC) tech-nique, microhardness tests, and transmission electron microscopy (TEM) observation. Com-posites fabricated with the 2024 alloy matrix were infiltrated through a ceramic preform using a squeeze-casting process. The alumina fibers had a considerable effect on the aging response of the matrix alloy in composites. Alumina fibers caused suppression of Guinier-Preston (GP) zone formation in composite that reduced the peak hardening during artificial aging. The suppression of GP zone formation in composites i believed to be due to the fiber-matrix inter-face, which acts as a sink for vacancies during quenching. Moreover, the presence of rein-forcement does not alter the kinetics of the subsequent artificial aging of these AI203/2024AI composites. I