Effects of various second phase ratios and contents on microstructure and mechanical properties of eutectic Sn58Bi alloy

A distinctive low melting point heterostructure alloy (LMH) Sn-Bi-Cu-Zn-Ag-Sb was prepared by introducing different ratios and contents of second phase into the eutectic Sn58Bi alloy (SBE). Rapid solidification results in a dispersion of Cu3Zn8, Ag3Sn, and SbSn precipitated phases in Sn53Bi3Cu3Zn2Ag2Sb (LMH32). Besides, the nano-sized eta'-Cu6Sn3 and Ag3Sn phases were also observed in the alloy matrix. During solidification, the Cu3Zn8 and Ag3Sn phases are used as the heterogeneous nucleation matrix of the Sn and Bi phases, which significantly refines the eutectic structure and leads to fine-grained strengthening. And the formation of Sn(Sb) solid solution phase leads to solid solution strengthening. The significant mechanical incompatibility between the matrix and the second phases of the LMHs produces a higher back stress hardening effect. The coupling effect of multiple strengthening mechanisms causes the ultimate tensile strength (UTS) of LMH32 reaches 102 MPa, higher 88.9% than that of SBE, and the elongation reaches 12.8%, but the melting point does not change significantly. (C) 2022 The Authors. Published by Elsevier Ltd.

Automated summary

A distinctive low melting point heterostructure alloy (LMH) Sn-Bi-Cu-Zn-Ag-Sb was prepared by introducing different ratios and contents of second phase, which showed improved mechanical properties, especially higher ultimate tensile strength and elongation.