Fatigue and fracture properties of submicron aluminum trioxide reinforced 6061 aluminum composite

Abstract

Many practical applications of structural components made from Metal Matrix Composites (MMC) involve cyclic loading. To ensure the structural integrity of components fabricated from the MMCs and to qualify for commercial applications, it must exhibit static and dynamic mechanical properties that are comparable and superior to those of conventional materials. In that respect, evaluation of fatigue and fracture properties becomes imperative during the development of a new material. There have been numerous studies which investigated the effect of large size reinforcements (few to ten micron in size) on the fatigue and fracture process in MMCs. However, no published data have been found which aimed to delineate the role of sub-micron size reinforcement. The main objective of the present work was to study the strain controlled fatigue, fatigue crack growth resistance and fracture toughness of 6061 aluminum alloy reinforced with sub-micron aluminum oxide particles of 10 and 20% volume fraction. The 10% Al2O3P reinforcement composite showed better strain controlled fatigue resistance when compared to the 20% reinforcement composite. Both the composites followed the Coffin-Manson and the Basquin's relationship. Among the two composites a higher fatigue ductility was observed for the 10% Al2O3 P reinforcement composite. The fatigue crack growth rate data indicated a slightly higher threshold stress intensity factor (ΔKth) in the 20% reinforcement composite. The fatigue crack growth rate in the Paris region was greater in 10% reinforcement composite when compared to the 20% reinforcement composite. The fracture toughness (KQ) for the 10 and 20% Al2O3 P reinforcement composites were obtained as 25.1 MPa [special characters omitted] and 18.1 MPa [special characters omitted] respectively.