Self-Diffusion of Cu and Sn in Single Crystal Cu₃Sn Ordered Alloys

抄録

Self-diffusion coefficients of ⁶⁴Cu and ¹¹³Sn in β phase and of ¹¹³Sn in γ phase single crystals of Cu–Sn alloys have been measured over the temperature range from 803 to 1024 K. In the β phase, Cu diffusivity is a factor of 1.7 to 3.1 larger than Sn diffusivity. The temperature dependence of the diffusivities of ⁶⁴Cu and ¹¹³Sn is, respectively, expressed as
D_Cu=(3.9_−1.5^+2.6)×10⁻⁷exp(−81.9±4.1kJ·mol⁻¹⁄RT)m²·s⁻¹,
D_Sn=(2.4_−0.7^+1.0)×10⁻⁵exp(−120.1±2.7kJ·mol⁻¹⁄RT)m²·s⁻¹.
In the γ phase the Arrhenius plot of Sn diffusivity exhibits a curvature, and can be expressed by two straight lines:
T>900 K D_Sn=(9.8_−0.7^+0.7)×10⁻⁵exp(−129.8±0.6kJ·mol⁻¹⁄RT)m²·s⁻¹,
T<900 K D_Sn=(8.3_−1.9^+2.5)×10⁻⁷exp(−94.1±1.9kJ·mol⁻¹⁄RT)m²·s⁻¹.
The higher diffusivity of Cu relative to that of Sn is consistent with the sublattice vacancy mechanism.