High resolution digital image correlation mapping of strain localization upon room and high temperature, high cycle fatigue of a TiAl intermetallic alloy

Microplasticity in a lamellar TiAl alloy upon high cycle tensile fatigue was measured by high resolution digital image correlation strain mapping at several stress and cycle increments, at 25 °C and 670 °C, for two lamellar thicknesses. Plastic deformation occurred primarily in soft-mode colonies at both temperatures, operating by slip parallel to the lamellae, and near lamellar interfaces. Plastic strains generally decreased to zero by the colony boundary; strain transfer across such boundaries was rare at both temperatures. At 25 °C, the maximum applied stress influenced the number of slip bands more so than did the number of loading cycles.