Effect of Aging Treatment on Microstructural Evolution of Rapidly Solidified Eutectic Sn-Pb Alloy Powders

Abstract

The microstructural stability of rapidly solidified eutectic Sn–Pb alloy solder powders was investigated through aging at room temperature (25 °C) and temperatures of 40 °C–120 °C. The coarsening behavior of the Pb-rich phase both at room and elevated temperatures was observed. The evident coarsening of the Pb-rich phase was detected upon storage after 40 days. At elevated temperatures, a similar sequence of Pb-rich phase coarsening was observed; however, it occurred substantially more quickly. Pb-rich coarsening rate kinetics at different temperatures were estimated using the Arrhenius equation. The apparent activation energy was 45.53 ± 4.23 KJ/mol, which indicates that grain boundary diffusion is a crucial mass transport mechanism controlling Pb-rich phase coarsening under annealing.

The Formation of the Structure of the Alloys of the Tin–Zinc System upon High-Speed Solidification

“…Solid solution crystals nonuniform in composition are formed at low rates of cooling [4,[8][9][10]. Increasing the rate of cool-ing to 10 6 K/s makes it possible to suppress diffusion in the liquid solution, increase the degree of homogene-ity of the alloys, and obtain abnormal supersaturation of the solid solution, which was observed in [11][12][13][14]. The expansion of the solubility limit of the compo-nents as a result of the high rates of cooling (10 5 -10 6 K/s) is associated with the deceleration or suppression of the origin of the second phase [15] and can be used for improving the characteristics of the materials which cannot be reached at low rates of cooling [16].…”

Joining Technology Innovations at the Macro, Micro, and Nano Levels

“…In another work focusing on the microstructure and fatigue damage of metal insert gas welding Al6082, incomplete penetration was identified as the dominant factor for limited welding strength [10]. For low-temperature soldering studies, Yan et al [11] studied the aging effect of Pb-rich phase on Sn-Pb alloys, and Xue et al [12] studied the effect of γ-irradiation on the formation of micro-voids. To enhance the bonding strength, Chen et al induced Cu to suppress the void formation in Sn-soldering [13], and Xue et al [14] used resin to strengthen the Pb-Bi solder paste.…”