GRAIN-BOUNDARY PENETRATION OF LIQUID SULFIDES IN NICKEL, COBALT, AND IRON

The attack on pure nickel, cobalt, and iron in the presence of pure sulphur vapours has been studied in the temperature range between 700 and 1150°C. The formation of liquid sulphides which penetrate along the grain boundaries of the solid metals has been detected. The dihedral angles have been measured as a function of temperature, and the temperature dependence of grain boundary andSolidi/liquid interfacial tensions have been computed. The kinetics of penetration of the liquid phase along the grain boundaries have been established and interpreted using Mullins'analysis.MST/248