In-situ observations of solutal melting using laser scanning confocal microscopy: The Cu/Ni model system - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Materials Characterization Année : 2014

In-situ observations of solutal melting using laser scanning confocal microscopy: The Cu/Ni model system

Julien Zollinger
Dominique Daloz
Miha Založnik
Hervé Combeau

Résumé

Solutal melting was investigated in-situ by means of high temperature laser scanning confocal microscopy. This technique enabled us to track the motion of the solid-liquid interface in order to determine the evolution of the interfacial velocity. The Cu-Ni binary system was chosen as a model case and concentric samples were fabricated from both pure metals. Two holding temperatures above the melting point of Cu were investigated, i.e., 1115 and 1145 degrees C. As the average composition of the mounted samples was chosen to lie within the solid solution region, the reaction occurred via the following steps: i) thermal melting of Cu, ii) solutal melting of Ni, and iii) resolidification. A smooth and regular s-1 interface was observed during solutal melting, except during a short period at 1145 degrees C where an irregularity briefly appeared. At 1115 degrees C, the dissolution of Ni was completed in less than 3 min and the total thickness dissolved was in the range 40-50 mu m. At 1145 degrees C, the dissolution did not last much longer but the total thickness dissolved was significantly larger: approximately 180 mu m. At both temperatures, the velocity first increased, then reached a maximum value after 20-30 s (0.6-0.8 mu m/s at 1115 degrees C and 4.8 mu m/s at 1145 degrees C), and finally tends progressively to zero. Post-mortem observations showed that the Ni was homogeneously dissolved over the entire sample height at 1115 degrees C, which excludes any effects of convection on the velocities that we measured. On the contrary, at 1145 degrees C, the dissolution was more important in the upper part of the sample and the interface appeared curved. The total thickness dissolved was in both cases larger than the predicted theoretical values and the melting velocities were also larger than the values obtained from finite difference calculations. The discrepancies are more pronounced at higher temperature.

Domaines

Matériaux
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Dates et versions

hal-01291907 , version 1 (22-03-2016)

Identifiants

Citer

Léa Deillon, Julien Zollinger, Dominique Daloz, Miha Založnik, Hervé Combeau. In-situ observations of solutal melting using laser scanning confocal microscopy: The Cu/Ni model system. Materials Characterization, 2014, 97, pp.125-131. ⟨10.1016/j.matchar.2014.09.004⟩. ⟨hal-01291907⟩
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