Resumen

KAISER, M. S.. Physical properties of Sn affected Cu through lead-free solder and combined effect of severe cold deformation and thermal ageing. J. appl. res. technol [online]. 2025, vol.23, n.1, pp.69-81.  Epub 22-Ago-2025. ISSN 2448-6736.  https://doi.org/10.22201/icat.24486736e.2025.23.1.2461.

The precipitation behavior of Cu, affected by lead free tin-based solder, is investigated as a function of cold deformation and artificial ageing using microhardness measurements, electrical resistivity, differential scanning calorimetry, reflectance behavior and microstructural observation. The physio-electrical properties of pure Cu are greatly enhanced by changes in parameters like cold rolling and ageing when Sn is added through the solder. Cold rolling shows the superior hardness for Sn doped alloys because of the dissimilar crystal orientation of the BCC of Sn precipitated within the FCC Cu matrix. That is why it increases electrical resistivity. Two processes, namely precipitation strengthening through supersaturated solid solution and recovery, as well as recrystallization softening, are observed for the alloys. Fine precipitates, which hinder dislocation movement, improve recrystallization temperature, as confirmed by the DSC study. A spectral reflectance study reveals that Sn doping provides lower percent reflectance whereas it improves under ageing treatment due to the formation of fine precipitates. Micrograph studies confirm elongated grains in their rolling direction, and relatively thick grain boundaries as the presence of different particles for minor added alloys. Ageing at 400ºC for one hour all samples attain equiaxed grain by reaching a more or less recrystallized state.

Palabras llave : Microstructure; minor accumulation; reflectance; resistivity; thermal ageing; work hardening.

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