Determination of the enthalpy of fusion and thermal diffusivity for ternary Cu_60-xSn_xSb₄₀ alloys

The liquidus and solidus temperatures, enthalpy of fusion, and the temperature dependence of thermal diffusivity for ternary Cu_60-xSn_xSb₄₀ alloys were systematically measured by DSC and laser flash methods. It is found that both the liquidus temperature and the enthalpy of fusion decrease with the rise of Sn content, and their relationships with alloy composition were established by polynomial functions. The thermal diffusivity usually drops from the solid toward the semi-solid state. The undercoolability of those liquid Cu_60-xSn_xSb₄₀ alloys with primary Cu₂Sb solid phase is stronger than the others with primary β(SnSb) intermetallic compound, and the increase of cooling rate facilitates further undercooling. Microstructural observation indicates that both of the primary Cu₂Sb and β(SnSb) intermetallic compounds in ternary Cu_60-xSn_xSb₄₀ alloys grow in faceted mode, and develop into coarse flakes and polygonal blocks.