Pure Cu was deformed at ultra-high strain-rates by the technique of cold spraying. It was found that after annealing the hardness of the samples did not fall as low as was known for heavily deformed Cu at normal strain rates, e.g., cold rolling. The reason for this was the presence of defects that did not heal out after annealing at 600C. These defects were identified as dislocation loops of the extrinsic and intrinsic kind. Possible mechanisms for the formation of these loops were discussed.

Formation of Persistent Dislocation Loops by Ultra-High Strain-Rate Deformation during Cold Spraying. C.Borchers, F.Gärtner, T.Stoltenhoff, H.Kreye: Acta Materialia, 2005, 53[10], 2991-3000