Effect of Sb and Zn Addition on the Microstructures and Tensile Properties of Sn-Bi-Based Alloys.

Akira Yamauchi,Masashi Kurose

doi:10.3390/ma15030884

Abstract

The tensile behavior of Sn–Bi–Cu and Sn–Bi–Ni alloys has been widely investigated. Reportedly, the addition of small amounts of a third element can refine the microstructures of the eutectic Sn-58mass% Bi solder and improve its ductility. However, the superplasticity mechanism of Sn-based alloys has not been clearly established. Therefore, in this study, the effects of Sb and Zn addition on the microstructures and tensile properties of Sn–Bi-based alloys were investigated. The alloys were subjected to tensile tests under various strain rates and temperatures. We found that Zn- and Sb-added Sn–Bi-based alloys demonstrated superplastic deformation at high temperatures and low strain rates. Sb addition significantly affected the elongation of the Sn–Bi–Sb alloys because the metal dissolves in both the primary Sn phase and the eutectic Sn–Bi matrix. The segregation of Zn and formation of needle-like Zn particles at the eutectic Sn–Bi phase boundary affected the superplastic deformation of the alloys. The deformation of the Sn–40Bi-based alloys at high temperatures and low strain rates led to dynamic recovery, dynamic recrystallization, and/or grain boundary slip because of the accumulation of voids.

Highlights

The use of Pb and Pb-containing products has been banned in many countries because of their harmful effects on the human body and environment [1,2]
SAC305 is unsuitable for some low-heatresistance components because its melting temperature, at approximately 494 K, is higher than that of the Sn–Pb eutectic solder (456 K)
All the alloys displayed chisel-point fractures, which indicate and low strain rates, which are conducive to superplastic behavior, specimens do not show plastic deformation

Summary

Introduction

The use of Pb and Pb-containing products has been banned in many countries because of their harmful effects on the human body and environment [1,2]. The Sn–Bi Pb-free solder alloys are characterized by a relatively high tensile strength and good creep resistance [11,12,13]. The superplasticity mechanism of Sn-based alloys has not Materials 2022, 15, 884 enhance the mechanical properties and wettability of Pb-free solders for green electronic devices [16,17,18,19,20,21,22]. The corresponding results that these alloys occupy a small solid-solution region in the and. Sn phase diagram and easilyCu form show superplasticity at high temperatures low strain rates [24,25]. Sn orofBielements on the superplastic deformation of the regions inalloy the phase diagrams. To confirm the superplastic superplastic deformation, thebehavior concentration the added element and evolution of microdeformation, thealso concentration structures were evaluated.of the added element and evolution of microstructures were evaluated

Materials and Methods

Discussion

Tensile

Conclusions