Interfacial Reactions in Model NiTi Shape Memory Alloy Fiber-Reinforced Sn Matrix “Smart” Composites

In this article, the microstructure properties of a novel Pb-free solder composite were examined. A binary nickel-titanium shape memory alloy (SMA) fiber was used to reinforce the Sn-rich matrix, to take advantage of the superelastic properties of the fiber. The objective of this study was to understand long-term, high-temperature interfacial growth in a model NiTi fiber-reinforced Sn matrix composite solder system. The microstructure was quantified by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and wavelength dispersive spectroscopy (WDS). The mechanical properties of the interfacial zone, e.g., Young's modulus and hardness, were characterized by nanoindentation. The evolution of the reaction products with time and the relationship between composition and local mechanical properties are discussed.