Lateral propagation of intermetallic phases in coarse- and nano-grained Cu/Sn diffusion couples

• Published in: Powder metallurgy and metal ceramics 2008-11, Vol.47 (11-12), p.652-659
• Main Authors: Kaganovskii, Yu. S., Paritskaya, L. N., Bogdanov, V. V.
• Format: Article
• Language: English
• Subjects: Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; COMPOSITES; Copper; Couples; DIFFUSION; Glass; Grain size; GRAIN SIZE AND SHAPE; INTERMETALLIC COMPOUNDS; KINETICS; Materials Science; Metallic Materials; MICROSTRUCTURES; Nanocomposites; Nanomaterials; Nanostructure; Natural Materials; PHASES; Propagation; Reaction kinetics; Spreading; Studies; THIN FILMS
• ISSN: 1068-1302; 1573-9066
• DOI: 10.1007/s11106-009-9074-2

The kinetics of lateral Cu 6 Sn 5 and Cu 3 Sn phase propagation in nano-grained thin-film and coarsegrained massive diffusion couples Cu–Sn is studied in a temperature range 160–180°C by optical microscopy, AFM, SEM, and energy-dispersive X-ray spectroscopy (EDS). To prevent surface diffusion and thus separate GB-diffusion contribution into the kinetics of phase propagation in nanograined structures, the surfaces of thin-film couples are covered by a thin carbon layer. It is found that the rates of lateral Cu 6 Sn 5 and Cu 3 Sn phase spreading in thin-film couples exceed several times the spreading rates of the same phases over the surface of coarse-grained samples. The kinetics of lateral phase spreading both in thin-film and in massive diffusion couples obeys parabolic law. The kinetics of the phase propagation in thin-film couples turns out to be independent of the film thickness (in the range 40–200 nm), whereas it is rather sensitive to the grain size and GB structure. A and B regimes of GB reactive diffusion are found in the spreading Cu 3 Sn phase. Theoretical analysis of the phase propagation kinetics accelerated by GB diffusion is done and the phase propagation rates are calculated.