THE WETTING TRANSITION IN HIGH AND LOW-ENERGY GRAIN-BOUNDARIES IN THE CU(IN) SYSTEM

Wetting of two symmetrical tilt grain boundaries, 77-degrees <110>, and 141-degrees <110>, in synthetic copper bicrystals with a Cu(In) melt was studied in the temperature range 690-990-degrees-C. The contact angle at the site of GB intersection with the solid-melt interface was measured. A wetting transition occurred at T(w) = 960 +/- 6-degrees-C for the 77-degrees <110> grain boundary and at T(w) = 930 +/- 5-degrees-C for the 141-degrees <110> grain boundary. The contact angle approached zero for this transition. The relative surface energies of the two boundaries were measured using the thermal grooving technique. The energy of the 77-degrees <110> grain boundary is about 40% lower than that of the 141-degrees <110> grain boundary. Therefore, it has been shown experimentally that the lower the grain boundary energy, the higher the wetting transition temperature. This is in agreement with the thermodynamic model of wetting transitions on grain boundaries.