Effect of rapid solidification and small additions of Zn and Bi on the structure and properties of Sn-Cu eutectic alloy

The Sn-Cu eutectic alloy has been produced by rapid solidification using the melt-spinning technique, and both Zn and Bi have been added individually to it, in the ratio 0.5 wt.%. X-ray diffraction (XRD) analysis and differential thermal analysis (DTA) have been carried out. Resistivity, Vickers microhardness (HV), and yield stress (σ_y) have been measured. Also a new method for measuring creep has been described using a HV tester. The creep measured by this method is termed “microcreep.” It is a quick, nondestructive method and requires a small sample, about 1 cm², with thickness 1 mm or less. The results show that formation of Cu₃₉Sn₁₁ occurs due to the addition of both Zn and Bi. The addition of Zn increases HV and σ_y, but slightly lowers the creep resistance; however, the addition of Bi deteriorates the creep resistance. Also, it is found that the creep rate of as-quenched melt-spun alloys is high.