Effects of Surface Superconductivity in Low-к Al-Ag Alloys
The supersaturated solid solution of silver in aluminum decomposes during an isothermal aging according to the following sequence: Guinier-Preston zones → γ΄ precipitates → γ precipitate (≃ Ag2A1).1 The Guinier-Preston zones are spherical, silver-rich (≃ 60 at. %) clusters, coherent with the matrix and of the same crystallographic structure, distributed at random in a depleted matrix. During the preprecipitation stage (Guinier-Preston zones) zones are growing with a coarsening process and the residual resistivity measured at 4.2°K is decreasing. When the diameter is about 100 Ǻ the precipitation of γ΄ phase begins.
KeywordsMagnetization Curve Supersaturated Solid Solution Residual Resistivity Isothermal Aging Meissner State
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