Abstract
Al and Zn are two of the most common alloying elements in commercial Mg alloys,
which can improve the physical properties through solid solution strengthening and precipitation
hardening. Diffusion plays a key role in the kinetics of these and other microstructural design
relevant to Mg-alloy development. However, there is a lack of multicomponent diffusion data
available for Mg alloys. Through solid-to-solid diffusion couples, diffusional interactions of Al
and Zn in ternary Mg solid-solution at 400° and 450°C were examined by an extension of the
Boltzmann-Matano analysis based on Onsager’s formalism. Concentration profiles of Mg-Al-Zn
ternary alloys were determined by electron probe microanalysis, and analyzed to determine the
ternary interdiffusion coefficients as a function of composition. Zn was determined to
interdiffuse the fastest, followed by Mg and Al. Appreciable diffusional interactions among Mg,
Al, and Zn were observed by variations in sign and magnitude of cross interdiffusion
coefficients. In particular, Zn was found to significantly influence the interdiffusion of Mg and
Al significantly: the and ternary cross interdiffusion coefficients were both negative,
and large in magnitude, in comparison to
and , respectively. Al and Mg were
observed influence the interdiffusion of Mg and Al, respectively, with positive and
interdiffusion coefficients, but their influence on the Zn interdiffusion was negligible.
