SMALL ATOM DIFFUSION AND BREAKDOWN ON STOKES-EINSTEIN RELATION IN THE SUPERCOOLED LIQUID STATE OF Zr-Ti-Cu-Ni-Be ALLOYS
نویسنده
چکیده
Be diffusivity data in the bulk metallic glass forming alloys Zr4i.2Ti13.sCu125Ni10Be22.s and Zr46.7Tis.3Cu75Ni10Bez7.s are reported for temperatures between 530K and 710K, extending up to SOK into the supercooled liquid states of the alloys. At the glass transition temperature, T g' a change in temperature dependence of the data is observed in both alloys, and above T g the diffusivity increases faster with temperature than below. The data in the supercooled liquid can be described by a modified Arrhenius expression containing the communal entropy of the supercooled liquid and based on a diffusion mechanism suggested earlier. The comparison with viscosity data in the supercooled liquid state of Zr46.7Ti8.3Cu75Ni10Be275 reveals a breakdown of the StokesEinstein relation, whereas D(T) and ll(T) follow a relation close to van den Beukel's. The breakdown of the StokesEinstein relation indicates a cooperative diffusion mechanism in the supercooled liquid state of the ZrTiCuNiBe alloys.
منابع مشابه
Small atom diffusion and breakdown of the Stokes–Einstein relation in the supercooled liquid state of the Zr46.7Ti8.3Cu7.5Ni10Be27.5 alloy
Be diffusivity data in the bulk metallic glass forming alloy Zr46.7Ti8.3Cu7.5Ni10Be27.5 are reported for temperatures between 530 and 710 K, extending 85 K into the supercooled liquid state of the alloy. At the glass transition temperature Tg, a change in temperature dependence of the data is observed, and above Tg the diffusivity increases more quickly with temperature than below. The data in ...
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