The long capillary and shear-cell techniques are traditionally used for diffusion measurements in liquid metals. Inspired by the idea of the shear-cell method, we have built a multi-slice sliding cell device for inter-diffusion measurements in liquid metals. The device is designed based on a linear sliding movement rather than a rotational shearing as used in the traditional shear-cell method. Compared with the normal shear-cell method, the present device is a more compact setup thus easier to handle. Also, it is expected to be easier to monitor with X-rays or neutrons if used in in situ experiments. A series of benchmark time-dependent diffusion experiments in Al-Cu melts carried out with the present technique reveal that accurate diffusion constants can be achieved only after a sufficient time. For short annealing times, the initial shearing process causing convective flow dominates the measurement and leads to an increase of the measured diffusion coefficient by a factor three. The diffusion data obtained for Al-Cu liquids are consistent with the most accurate data measured by the in situ X-ray radiography method under well controlled conditions of no temperature gradient or other perturbation. High accuracy and easy handling as well as superior adaptability make the present technique suitable for diffusion studies in liquid metals.

It is a significantly difficult problem to obtain the diffusion coefficients by analyzing the concentration profiles in multicomponent melts. Here, based on the Onsager reciprocal relations, we report a new analysis method, which can achieve the diffusion coefficient matrix by fitting the concentration profiles under a given diffusion time. Our method allows us to obtain the interdiffusion coefficient matrix in a multicomponent system via just a single diffusion couple experiment. Thus, it shows obvious merits compared to the previously reported diffusion path method and the square root diffusivity method. As a qualifying example, the four independent interdiffusion coefficients in a Ce–Al–Cu ternary liquid alloy have been derived from the concentration profiles measured by the multi-slice sliding cell technique. It is demonstrated that such a single experiment analysis method shows great potential for wide use in a multicomponent system.

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