Abstract:The wettability and wetting interface morphology of Sn-8.8Zn-xBi alloy on NdFeB substrate in Ar-5% H2 atmosphere were investigated by the seated drop method. The results show that the wetting process of Sn-8.8Zn-xBi alloy on NdFeB substrate is divided into two stages: a non-reactive wetting stage driven by van der Waals and diffusion forces, and a reactive wetting stage influenced by the interfacial reaction products and the adsorption of the reaction products. The wettability of Sn-8.8Zn-xBi alloy is improved with the increase of Bi content, and the wetting time is shortened under the same heating condition, in which the contact angle of Sn-8.8Zn-7Bi alloy on the surface of NdFeB substrate is 120.11°. The wetting type of the Sn-8.8Zn-xBi alloy on the NdFeB substrate is the reactive wetting, and the reaction product is ζ-FeZn13 phase. ζ-FeZn13 phase improves the bond strength of Sn-8.8Zn-xBi alloy on the NdFeB surface, which proves that Sn-8.8Zn-xBi alloy can be used as NdFeB surface solder.