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Berlin 2015 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 42: Mechanical Properties I

MM 42.5: Talk

Wednesday, March 18, 2015, 17:00–17:15, TC 010

Refined statistical work hardening and recovery model for Aluminium alloys — •Volker Mohles1, Volker Pankoke1, Philipp Schumacher2, and Benjamin Milkereit21RWTH Aachen University, Institute of Physical Metallurgy and Metal Physics, Aachen, Germany — 2University of Rostock, Chair of Materials Science, Rostock, Germany

A new statistical work hardening and recovery model for aluminium alloys called 4IVM (4 Internal Variables Model) has been developed. Like its established predecessor (3IVM+) it calculates the evolution of dislocation densities during plastic deformation and derives the corresponding flow curves in a wide range of temperatures and strain rates. In order to improve the physical basis and its applicability, the new model considers four densities of dislocations as material state variables: mobile dislocations (ρmob), dipole dislocations (ρdip), locked dislocations (ρlock), and subgrain boundary dislocations (ρsub). These dislocation types have distinctly different properties, in reality and in the model, with respect to generation, annihilation, direct impact on the flow stress, and the overall dislocation density evolution. Moreover their cores and strain fields differ. In future this allows to introduce specific dependencies on segregation by foreign solved atoms. The new model is validated by comparing simulated flow curves to measured ones. For this, binary Al-Si alloys have been prepared and compression tested in varying precipitation states. Compared to its predecessor, 4IVM offers improved flow curve predictions.

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