Conferences

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

Yu.S.Kaganovskii,
 
L.N.Paritskaya,
 
V.V.Bogdanov
 

Powder Metallurgy - Kiev: Frantsevich Institute for Problems of Materials Science NASU, 2008, #11/12
http://www.materials.kiev.ua/article/1313

Abstract

The kinetics of lateral Cu6Sn5 and Cu3Sn phase propagation in nano-grained thin-film and coarse-grained massive diffusion couples Cu-Sn were 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 kinetics of phase propagation in nano-grained structures, the surfaces of thin-film couples were covered by a thin carbon layer. It was found that the rates of lateral Cu6Sn5 and Cu3Sn phase spreading in thin-film couples exceed several times the spreading rates of the same phases over the surface of coarse-grained samples. 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 turned out independent of the film thickness (in the range 40 – 200 nm), whereas it was rather sensitive to the grain size and GB structure. A and B regimes of GB reactive diffusion were found in the spreading Cu3Sn phase. Theoretical analysis of the phase propagation kinetics accelerated by GB diffusion has been done and the phase propagation rates have been calculated.


COARSE-GRAINED MASSIVE POLYCRYSTALS, CU-SN NANO-GRAINED THIN FILMS, INTERMETALLIC PHASES, LATERAL PHASE PROPAGATION, REACTIVE SURFACE AND GRAIN BOUNDARY DIFFUSION, SURFACE AND GRAIN BOUNDARY DIFFUSION COEFFICIENTS