Bi Dispersion Hardening in Sn-Bi Alloys by Solid-State Aging

• Published in: JOM (1989) Vol. 75; no. 11; pp. 4922 - 4930
• Main Author: Shen, Yu-An
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-11-2023; Springer Nature B.V
• Subjects: Aging; Aging (metallurgy); Alloys; Aluminum; Bismuth; Chemistry/Food Science; Dispersion hardening alloys; Earth Sciences; Engineering; Environment; Hardness; Intermetallic compounds; Mechanical properties; Melting points; Physics; Precipitation hardening; Solid solutions; Technical Article; Temperature; Thermodynamic properties; Tin base alloys; Wettability; United States > US; Japan
• ISSN: 1047-4838; 1543-1851
• DOI: 10.1007/s11837-023-06079-9

In this study, Bi was added to pure Sn to improve its strength and thermal properties. The presence of 2.5 and 5 wt.% Bi in the Sn matrix lowered the melting point of Sn from 232°C to 229°C and 225°C, respectively. The hardness was improved by increasing the Bi content; 2.5 wt.% Bi caused solid-solution hardening, whereas 5 wt.% Bi caused solid-solution, fine-grain, and Bi precipitation hardening. Sn with 5 wt.% Bi was reinforced by aging, which was attributed to dispersion hardening by Bi redistribution in the Sn matrix, and possessed good wettability on Cu. This study demonstrated that Sn with 5 wt.% Bi with good wettability has a good melting point, excellent hardness, and aging enhancement compared to pure Sn. Thus, this study provides mechanistic insights into the hardening of Sn-Bi alloys.