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RESEARCH PRODUCT

Melting Process of the Sn-45 wt.% In and Sn-77 wt.% In Alloys as Viewed by Positron Annihilation

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The temperature dependences of the positron annihilation parameters F and R were determined for Sn–45 wt.% In and Sn–77 wt.% In alloys. The obtained results enabled to verify the vacancy and the quasicrystalline models of the melting process. It was found that for metals transforming into the liquid state from the structures different than the close packed structure, the melting transition are hardly explainable in terms of the vacancy model of melting. The strong trapping of positrons in metallic liquids is an indication of the presence of microvoids (vacancy clusters) or microcrystals containing defects more immense than vacancies. The share of these positron trapping centers in the volume of metallic liquids is constant or decreases with increasing temperature. The obtained results demonstrate the particular applicability of the positron annihilation method for studies of defect kinetics in metallic liquids.