Abstract
Interfacial reactions in Bi/Ni, Sn/Co, and Sn/Te systems that exhibit unique cruciform pattern formation are investigated. Different from the couples examined in the past, the solid substrates, NI, Co, and Te, are placed outside the couples while constituents of low melting temperature, Bi and Sn, are placed In the center. With interfacial reactions proceeding In these couples, the reaction products grow Inwardly at reentrant corners, and shrinking of thereaction layer at the comer is observed. As a result of the volumetric changes caused by interfacial reactions, stresses arc built up in the couples, and stress-intensified locations are found at reentrant comers. The built-up stresses alter the diffusion rates and thus retard the reactionat the comers. Instead of forming cruciform patterns, the inner reactant Is of flat shuriken shape after reactions. © 2010 Materials Research Society.