Solute clusters represent the start of decomposition during aging of aluminum alloys and can generate strengthening while keeping the strain hardening high in comparison with shearable precipitates. In this study, clusters in a pre-aged AlMgSiCu 6xxx-series and a recently developed AlMgZnCu crossover alloy were investigated by atom probe tomography (APT) and tensile testing before and after straining. Pre-aging was performed at 100 ◦C and 60 ◦C respectively, and a tensile strain of 5% was applied. The key feature detected was the formation of clusters during plastic deformation, referred to here as “strain-induced clustering”. It is explained based on diffusion enhancement by the strain-induced formation of excess vacancies during tensile testing, and evaluated by means of a simple modeling approach. In addition to the significant intrinsic contribution of clusters to strain hardening via dislocations, strain-induced clustering adds a hypothetical non-dislocation-based component to strain hardening.
Bibliographische NotizFunding Information:
This work was funded by the Christian Doppler Research Association within the framework of the Christian Doppler Laboratory for Advanced Aluminum Alloys. Financial support from the Austrian Federal Ministry for Digital and Economic Affairs, the National Foundation for Research, Technology and Development and the Christian Doppler Research Association is gratefully acknowledged. The authors wish to express their sincere thanks to AMAG Rolling for the valuable discussions. We also thank Maximilian Schiester for his support in conducting the APT measurements.