T. E. J. Edwards; F. Di Gioacchino; A. J. Goodfellow; W. J. Clegg
International Journal of Fatigue 124 (2019) 520-527
Microcompression testpieces of a lamellar γ-TiAl alloy were high cycle fatigued up to 10 5 cycles at stress ratios of 0.5–0.7, to maximum stresses above and below the yield stress. The localised deformation was studied by nano-scale digital image correlation strain mapping of a Pt patterned side-face of the pillars. With crystal orientation mapping, the fatigue deformation lines were found to locate at the γ/γ and γ/α 2 lamellar interfaces. The deformation lines were closely spaced slip lines in transmission electron imaging. Gradients of shear strain developed along the deformation lines, increasing in magnitude as cycling progressed. Extensive transverse twinning also occurred.