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• Nanoscale digital image correlation (HR-DIC) strain mapping of HCF up to 670 °C. • Microplasticity mainly in softmode colonies: parallel to lamellae, near interfaces. • Poor strain transfer across colony boundaries at both temperatures. • At 25 °C, maximum stress influenced the slip band count more than did the cycle count. 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. [ABSTRACT FROM AUTHOR]