Dresden 2026 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 21: Phase Transformations II

MM 21.9: Talk

Wednesday, March 11, 2026, 12:30–12:45, SCH/A215

In-situ view on contact and solutal melting of Al-Cu — •Florian Kargl^1,2, Matthias Kolbe¹, and Nagarjuna Remalli¹ — ¹Institute for Frontier Materials on Earth and in Space, German Aerospace Center, Cologne, Germany — ²Foundry Institute, Fundamentals of Solidification, RWTH Aachen University, Aachen, Germany

Melting plays an important role in many technical processes such as casting, additive manufacturing, etc. but is far less understood than solidification. We report on the kinetics of the solid-liquid interface during contact and solutal melting of Al-Cu melting couples. Al-Cu melting couples consisting of an Al-annulus and a Cu-disc in close contact were processed in an isothermal temperature field. The melting process was in-situ monitored with X-radiography with a sub-second time resolution determining interface kinetics and liquid composition changes. For contact melting a temperature below the melting points of Al and Cu but above the eutectic temperature was chosen. For solutal melting the sample was processed above the melting point of Al. We observed contact melting to be initiated along Cu-grain boundaries with intermetallic layers representing the entire phase diagram forming between the liquid and the still solid Cu. The layer structure has been verified post-mortem by optical imaging and quantified by SEM-EDX. Solutal melting was found to be dependent on sample thickness with buoyancy convection increasing the reaction speed in thicker samples. Further, asymmetric reaction patterns were observed to arise due to Al2O3-layer build-up and/or initial Al2O3-presence at the Al-Cu interface and/or partial Al-detachment during melting.

Keywords: Al-Cu alloys; melting phenomena; buoyancy convection; grain boundary diffusion; X-radiography