A study of the effects of particle 3-dimensional geometry and micro-texture on fatigue crack initiation behaviors in an Al-Cu alloy using focused ion beam and electron backscatter diffraction

Multiple cracks were generated from surface particles in an Al-Cu alloy in four-point bend fatigue. These cracks mostly became non-propagating at or shortly beyond the particle/matrix interface on the surface. Cross-sectioning using focused ion beam revealed that the 3-dimensional geometry, especially the thickness, of fractured particles was the key factor controlling the driving force for micro-crack growth. The resistance to micro-crack growth was mainly associated with crack plane twist at the particle/matrix interface, as revealed by electron backscatter diffraction measurement.