Surface effects on the sintering behavior of nanometric metallic particles

Nanometric Fe and Cu powders (NP) were sintered in H-2 after uniaxial cold pressing. The sintering behavior of samples was studied using dilatometric and calorimetric techniques. The sintering temperature T-d and the self-dif fusion activation energy Q(a) obtained in H-2 for Fe were 350 degrees C and 60 kJ/mole respectively, and those obtained in H-2 for Cu were of 220 degr ees C and 43 kJ/mole. According to the present results, the activation ener gies obtained from both NP in H-2 could be associated to those for self-dif fusion in the liquid state (Fe 65 kJ/mole and Cu 41 kJ/mole). Assuming T-d related to the surface melting temperature, the size dependence of surface melting of nanometric metallic particles is proposed on the basis of a simp le Debye model together with the Lindemann law, by phenomenologically takin g into account a surface phonon softening process.