Pinning points which anchored Shockley dislocations and ordinary dislocations, in the γ-phase of a single-phase alloy or a lamellar 2-phase alloy, were studied by performing in situ straining experiments inside a transmission electron microscope. The overcoming of these pinning points was observed, and the density of the latter was measured. The results indicated that the pinning points were extrinsic to the dislocations. The measured densities did not correspond to an homogeneous distribution of individual O atoms in the crystal. It was proposed that they were due to segregation of some of the interstitial O atoms.

Pinning-Points Anchoring Ordinary and Shockley Dislocations in TiAl Alloys. S.Zghal, A.Menand, A.Couret: Acta Materialia, 1998, 46[16], 5899-905