Investigation of fatigue behaviors of Al6061 matrix marble powder reinforced composite

Abstract

In the present study, we focused on the usability of waste marble powder (MP) as a reinforcement in Metal Matrix Composites (MMCs) and its compatibility with SiC and Al2O3. Al6061 alloy, which is frequently used in the aerospace industry, was chosen as the matrix. Composites were fabricated using reinforcements with 22-59 mu m powder size at different reinforcement-volume ratios. Two-stage stir casting method was used in the production of composites. The microstructures of the composites were visualized by scanning electron microscopy to determine the presence of reinforcements. The hardness of the composites was determined by the Brinell hardness measurement method. For the fatigue strength of the composites, the number of cycles was measured for 9 different stress values using a rotational bending fatigue device until the specimens ruptured. The addition of 5% marble powder to the Al6061 alloy increased the hardness by 20.69%, reaching 70 HBN. In binary hybrid composites, the highest hardness value was measured at 95 HBN in the sample reinforced with 3% SiC and 5% MP. For ternary hybrid composites, the hardness value of the composite containing 3% SiC, 3% Al2O3, and 5% MP was found to be 109 HBN. In the rotational bending fatigue test, the Al6061 alloy fractured after 820,783 cycles at a stress value of 100 MPa. However, with the addition of 5% MP to the matrix, the number of cycles approximately doubled to 1,643,127. Hardness measurement results showed that the marble powder can be almost as effective as SiC and Al2O3 in increasing the hardness of the composite. Marble powder reinforcement also increased the fatigue strength of the composites like other reinforcements.