Deciphering the effect of microstructural heterogeneities on the macro- and micro-mechanical behaviour of additively manufactured high-strength aluminium alloys

Materials & Design, vol. 270, pp. 116923

Abstract

Additively manufactured high-strength aluminum (Al) alloys exhibit exceptional strength and reasonable ductility, since they benefit from the heterogeneous as-built grain structure with alternating fine and coarse grains at the melt-pool boundaries and melt-pool interiors, respectively. Although the formation of such microstructures has been studied extensively, the nature of deformation at low length scales, specifically the complex interplay and individual contribution of microstructural heterogeneities, remains largely unexplored. The high-strength Al alloy Scalmalloy® was processed by PBF-LB/M. Its deformation behavior was investigated by macroscopic tensile tests performed at different temperatures and strain rates as well as by microscopic tensile tests in conjunction with high-resolution digital image correlation (µDIC). Specifically, the strain localization patterns as well as strain partitioning between the alternating fine and coarse grains were quantitatively analyzed. Inhomogeneous deformation behavior was observed in macroscopic tests in the form of temperature and strain rate-dependent serrated flow. µDIC and interrupted tensile EBSD results revealed severe strain and geometrically necessary dislocation density localizations near the interface between fine and coarse grains. Multiple microstructural heterogeneities like grain clusters, local L1 2 precipitate fraction and dislocation distribution were identified as decisive factors contributing to inhomogeneous micro- and macro-scale plasticity.

Authors 7

1. Soudip Basu corresponding

   Technische Universität Berlin

   Affiliation as printed

   Materials for Additive Manufacturing, Technische Universität Berlin 10623 Berlin, Germany

2. S. Murugesan Aachen Steel Institute

   RWTH Aachen University

   Affiliation as printed

   Steel Institute, RWTH Aachen University, 52072 Aachen, Germany

3. J. Gehlmann Aachen Central Facility for Electron Microscopy

   RWTH Aachen University

   Affiliation as printed

   Central Facility for Electron Microscopy (GFE), RWTH Aachen University, 52074 Aachen, Germany

4. Nicolas J. Peter

   Forschungszentrum Jülich

   Affiliation as printed

   Institute of Energy Materials and Devices (IMD-1), Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Strasse, 52428 Jülich, Germany

5. Avinash Hariharan

   Max-Planck-Institut für Nachhaltige Materialien

   Affiliation as printed

   Max Planck Institute for Sustainable Materials, 40237 Düsseldorf, Germany

6. F. Brasche

   Technische Universität Berlin

   Affiliation as printed

   Materials for Additive Manufacturing, Technische Universität Berlin 10623 Berlin, Germany

7. Christian Haase corresponding

   Technische Universität Berlin

   Affiliation as printed

   Center for 3D Technologies, Technische Universität Berlin 10623 Berlin, Germany

   Materials for Additive Manufacturing, Technische Universität Berlin 10623 Berlin, Germany