Study on the properties of Zn–xNi high temperature solder alloys

Zn based lead free solder for high temperature applications was developed by the addition of Ni. The effect of Ni content on the characteristics of the solder such as change in microstructure, melting behavior, thermal properties and mechanical properties were investigated. The microstructures of the solders changed significantly on increasing Ni content. Optical and SEM micrographs showed a dramatic increase in both size and quantity of Zn–Ni intermetallic particles with the Ni content. Moreover the area fraction of these intermetallics (IMCs) was also quantified with an image analyzing software. The formation of γ phase rather than δ phase was observed in the microstructure of Zn–Ni systems. The structural changes improved the mechanical properties like tensile strength and hardness of the newly developed binary alloys. Fascinatingly melting behavior of the solder alloys studied by DTA analysis revealed that the melting temperature of the composite solders remained unchanged with Ni addition. TMA analysis revealed that the co-efficient of thermal expansion decreased on increasing Ni content.