Diffusion of Zinc in Two-phase Mg-AI Alloy

摘要

Coefficient of ~(65)Zn heterodiffusion in Mg_(17)Al_(12) intermetllic and in eutectic alloy Mg-33.4 wt.% Al was measured in the temperature region 598-698 K using serial sectioning and residual activity methods. Diffusion coefficient of ~(65)Zn in the intermetallic can be written as D_I=1.7×10~(-2) m~2s~(-1) exp (-155.0 kJ mel~(-1)/RT). At temperatures T≥648 K, where the mean diffusion path was greater than the mean interlamellar distance in the eutectic, the effective diffusion coefficient D_(ef)=2.7×10~(-2)m~2s~(-1)exp(-155.1 kJ mol~(-1)/RT) was evaluated. At wto lower temperatures, the diffusion coefficients ~(65)Zn in interphase boundaries were estimated:D_b(623K)=1.6×10~(-12)M~2S~(-1) and D_b (598K)= 4.4 × 10~(-13) m~2s~(-1).