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MM: Fachverband Metall- und Materialphysik

MM 22: Mechanical properties I - Plastic deformation & fracture

MM 22.2: Vortrag

Dienstag, 1. April 2014, 10:30–10:45, IFW B

Microstructural influences on inhomogeneous plastic flow in AA2198 — •Henry Ovri and Erica Lilleodden — Helmholtz Zentrum Geesthacht, Institute of Materials Research, Materials Mechanics, Geesthacht, Germany

Inhomogeneous plastic flow has been reported in several Al alloys and is known to severely limit the formability of sheet metals and promote the formation of undesirable striations on the surface of the deforming part. Understanding the micromechanisms responsible for the occurrence of these plastic instabilities is pivotal to the design of alloys and process routes that mitigate the effect. Although it is widely accepted that the phenomenon is associated with dynamic strain aging (DSA) and negative stain rate sensitivity (NSRS), the effect of precipitation in retarding or enhancing the instabilities is still not clear. In this work, the effect of precipitation on inhomogeneous plastic flow in an Al-Li based alloy (AA2198) is investigated by using nanoindentation, atom probe microscopy and in situ TEM straining methods. The results are discussed on the basis of the observed interactions between matrix dislocations and coherent ordered δ ′ (Al₃Li) precipitates, residual matrix solute content and dislocation-particle interaction theories.