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Laterally-resolved formation mechanism of a lithium-based conversion layer at the matrix and intermetallic particles in aerospace aluminium alloys Vrije Universiteit Brussel

Ali Kosari, Frans Tichelaar, Peter Visser, H. Zandbergen, Herman Terryn, Johannes M. C. Mol

Lithium leaching coatings have recently been developed as eco-friendly active corrosion protection technology for aerospace aluminium alloys (AAs) by the formation of a conversion layer at coating defects. While general conversion layer formation characteristics were studied and reported before, here we study the local layer formation process with sub-micron resolution at and around intermetallic particles (IMPs) in AA2024-T3. Top- and ...

Dealloying-driven local corrosion by intermetallic constituent particles and dispersoids in aerospace aluminium alloys Vrije Universiteit Brussel

Ali Kosari, Frans Tichelaar, Peter Visser, H. Zandbergen, Herman Terryn, Johannes M. C. Mol

Nanoscopic characterization of heterogeneous intermetallic particles (IMPs) which microstructurally and compositionally evolve during local corrosion is crucial in unravelling the mechanisms and sequence of initial and local corrosion events. Herein, we study site-specific initiation events focused on microscopic constituent intermetallic compounds and nanoscopic dispersoids in AA2024-T3 at the nanoscale using a combined quasi in-situ and ...

On the use of AES data analysis to determine local enrichments of conversion coating elements at intermetallic particles on rolled Al Vrije Universiteit Brussel

Pieter Bouckenooge, Herman Terryn, Oliver Bauer, Katrin Eckhard
In this paper, the behaviour of the industrial applied Ti/Zr conversion coating (CC)
pretreatment on rolled automotive aluminium samples (AA5182) is analysed. Due to
its nanometre lateral and depth resolution, Auger electron spectroscopy (AES) is used
to analyse the CC distribution at surface cathodic intermetallic particles. As a result
of its high surface sensitivity, the AES technique is very susceptible to differences in ...

Editors' Choice - Dealloying-Driven Cerium Precipitation on Intermetallic Particles in Aerospace Aluminium Alloys Vrije Universiteit Brussel

Ali Kosari, M Ahmadi, Frans Tichelaar, Peter Visser, Yaiza Gonzalez-Garcia, H. Zandbergen, Herman Terryn, Johannes M. C. Mol

Cerium-based compounds have been studied for decades as non-toxic candidates for the protection of aerospace aluminium alloys (AAs) like AA2024-T3. However, the complex heterogeneous microstructure of these alloys has hindered a thorough understanding of the subsequent stages of corrosion protection provided by this class of inhibitors. Thus, this work is devoted to unravelling the interaction mechanisms of different intermetallic particles ...

Modeling localized aluminum alloy corrosion in chloride solutions under non-equilibrium conditions: Steps toward understanding pitting initiation Vrije Universiteit Brussel

Levente-Csaba Abodi, James Derose, Steven Van Damme, Andrei stefan Demeter, Johan Deconinck
A multi ion transport and reaction model has been developed with the intent to improve via simulation the understanding of the first steps of localized corrosion (pitting) of aluminum alloys at the microscale. However, the onset of pitting could not be predicted, but the simulation of all parts of a micropolarization curve, excluding the pitting regime, was possible. Unlike previous models, the model does not use the assumption that the system ...

Single point incremental forming of an aged Al-Cu-Mg alloy: Influence of pre-heat treatment and warm forming KU Leuven

Amirahmad Mohammadi, Ling Qin, Hans Vanhove, Marc Seefeldt, Albert Van Bael, Joost Duflou
This research is aimed at enhancing the poor room temperature formability of heat-treatable aluminum alloy AA2024-T3, without deterioration of its post-forming properties. For this purpose, the influences of different heat-treatment conditions as well as warm forming on the single point incremental forming formability and post-forming properties of this material were investigated. Thermal pre-treatments were consisting of annealing (O-temper), ...

Effect of simulated brazing on the microstructure and corrosion behavior of twin roll cast AA3003 Vrije Universiteit Brussel

Donovan Verkens, Reynier I. Revilla, Ali Kosari, Mert Gunyuz, Cemil Isiksacan, Johannes M. C. Mol, Iris De Graeve, Herman Terryn

Aluminum alloy (AA) 3003 is widely used as fin and tube material in heat exchangers. In these heat exchangers, the tube and fin material are brazed together by means of an AA4xxx alloy. In this study, the effect of a simulated brazing step on the microstructure and corrosion behavior of a twin roll casted (TRC) AA3003 was studied. In particular, the effect of simulated brazing on the corrosion properties of the centre line segregation (CLS) ...

Effect of Fe2O3 content on microstructure of Al powder consolidated parts via selective laser melting using various laser powers and speeds KU Leuven

Sasan Dadbakhsh
In situ constituents were formed inside an aluminium matrix via selective laser melting (SLM) of Al powder mixed with 5, 10, and 15 wt% Fe 2O3 powder (using various laser powers and speeds), in order to investigate the effect of Fe2O3 content on the microstructural characteristics of novel aluminium matrix composites. The unique microstructures such as coralline-like Al-Fe intermetallics were formed by the in situ reaction, being Fe3Al at first ...

Microstructure and degradation performance of biodegradable Mg-Si-Sr implant alloys KU Leuven

Andrea Gil Santos, Iñigo Marco, Nele Moelans, Omer Van der Biest
In this work the microstructure and degradation behavior of several as-cast alloy compositions belonging to the Mg rich corner of the Mg-Si-Sr system are presented and related. The intermetallic phases are identified and analyzed describing the microstructure evolution during solidification. It is intended in this work to obtain insight in the behavior of the ternary alloys in in vitro tests and to analyze the degradation behavior of the alloys ...

In situ particle layer formation in a Al-Mn-Si ternary eutectic alloy: Ground reference and microgravity experiments KU Leuven

Bin Zhou, Ludo Froyen
A special type of divorced eutectic growth mode (symbiotic growth) in a ternary Al-Mn-Si alloy, triggered by addition of titanium boride (TiB2) has been studied under both ground and microgravity conditions. During directional solidification, α (AlMnSi) particles nucleate ahead of the planar solidification front and are pushed and later engulfed by the interface forming a banded particle layer structure. The presence of fine titanium boride ...