SOLUTE INDUCED HARDENING NEAR GRAIN BOUNDARIES IN ZONE REFINED METALS

Microhardness studies of zone refined metals (Pb, Sn, Zn) doped with various solutes indicate that a certain class of solute atoms results in excess hardening near the grain boundary, while another class of solute atoms gives a region which is softer near the grain boundary than in the grain. As a result of the experimental observations, a solute-clustering model is proposed for grain boundary quench-hardening based on preferential solute-vacancy interactions and non-ideal thermodynamic behavior of the binary system. The present mechanism may have important implications to impurity-segregation problems at interfaces in both metallic and non-metallic systems. © 1968.