Microstructural aspects of formation and growth of short cracks in the Al(6061)/Al2O3 composite under LCF loading

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Fatigue cracks arise in the composite Al(6061)/Al2O3-T6 under LCF loading as transcrystalline cracks in connection with extrusions and intrusions. New cracks are permanently created. They propagate in interaction with the microstructure and form crack fields. The aim of this project is a research on the microstructural aspects of the initiation and growth of short fatigue cracks in the particle-reinforced Al(6061)/Al2O3-T6 composite. The grain orientations and, in particular, the spatial arrangement of the reinforcing phase within the ductile matrix phase influence the formation of deformation pattern in which the transcrystalline fatigue cracks are generated and propagate.It is planned to combine experimental methods (LCF, REM, EBSD, digital correlation of SEM pictures and tomograms (DIC) to measure deformation fields) with FE simulations. On the basis of the experimental data, 2- and 3-dimensional FE models of microstructure will be set up to simulate the crack path under cyclic loading. The crack propagation and the plastic zones around the crack tip(s) will be recorded experimentally at different stages of fatigue life and compared to the results of simulation. These combination of methods and microstructural background information will make it possible to better understand the propagation kinetics of short fatigue cracks in a two-phase material.