The influence of grain boundary sulfur concentration on the intergranular brittleness of nickel of different purities

When systematically combined, tensile tests at -150 °C and analysis by AES (Auger Electron Spectroscopy) or by electron probe reveal the mechanical and chemical effects of sulfur in the grain boundaries of nickel of different purities. The sulfur concentration in the grain boundaries of nickels containing globally less than 450 ppm S appears to be the essential factor in the grain boundary brittleness of the metal. Other elements may however interfere with the sulfur in the mechanical characteristics of the metal, either by increasing or decreasing the brittleness according to the particular case. They also interfere with the sulfur by slowing down the kinetics of the approach to equilibrium. Formerly Research Associate, Département de Métallurgie, Ecole Nationale Supérieure des Mines de Saint-Etiénne Formerly Professor, Département de Métallurgie, Formerly Professor, Département de Métallurgie,