Abstract
The isothermal section of the Sn-Cu-Ni system at 800°C has been experimentally determined. There is no ternary compound. A solid solution with a very wide compositional range, the γ phase is formed between the Ni 3 Sn(H) phase and Cu 4 Sn(H) phase; however, both of these two binary phases are not stable at 800°C. The binary Ni 3 Sn 2 phase also has extensive ternary solubility. The homogeneity ranges of both the γ and Ni 3 Sn 2 phases are very large in parallel to the Cu-Ni side, but relatively narrow along the Sn direction. This phenomenon indicates that Cu and Ni are exchangeable in both phases. Three kinds of reaction couples, Sn-55 at. pct Cu/Ni, Sn-65 at. pct Cu/Ni, and Sn-75 at. pct Cu/Ni, were prepared and reacted at 800°C for 5 to 20 minutes. The reaction paths are liquid/Ni 3 Sn 2 /γ/Ni 3 Sn(L)/Ni for the Sn-55 at. pct Cu/Ni and Sn-65 at. pct Cu/Ni couples, and the reaction path is liquid/γ/Ni 3 Sn(L)/Ni for the Sn-75 at. pct Ni couples.