Investigation of anisotropic diffusion behavior of Zn in hcp Mg and interdiffusion coefficients of intermediate phases in the Mg-Zn system

The anisotropic diffusion behavior of Zn in hcp Mg was for the first time experimentally investigated using diffusion couple experiments with Mg single crystals at temperatures between 553 and 603 K (280 and 330 °C). The diffusion coefficients determined from Zn concentration profiles in hcp Mg single crystals are: D⊥hcp−MgZn=4.98×10−5exp(−132725/RT) m2/s along the basal plane and Dllhcp−MgZn=7.33×10−5exp(−135488/RT) m2/s normal to the basal plane. The diffusion coefficient of Zn along the basal plane is about 1.23 times higher than the one normal to the basal plane at the experimental temperatures. Inter-diffusion coefficients of Mg2Zn3, MgZn2 and Mg2Zn11 were experimentally determined for the first time. In addition, the inter-diffusion coefficients of Mg12Zn13 and Mg51Zn20 were calculated from a multiphase diffusion model.