Viscoelastic Properties of Thixotropic Semisolid Alloy Relating the Microstructure

摘要

The subject of this work is to investigate viscoelastic properties such as loss modulus (G"), storage modulus (G'), complex shear modulus (G*), complex viscosity (η*) and loss angle (δ) at different temperatures by means of a small-amplitude oscillatory test. These properties allow to provide information about materials structure. For this purpose, we employed a tin-lead alloy (Sn-15%Pb) which exhibits a similar microstructure to aluminum alloys and is the classic alloy for semisolid thixotropic studies. It is interesting to note that the Sn-15%Pb alloy exhibits a slightly decrease in storage modulus (G') over the entire frequency (0.01-10Hz) at high temperatures, showing its viscoelastic behavior. In addition, a detailed analysis of master curves (oscillatory tests) was made to relate the semisolid microstructure (solid fraction) with the plateau modulus (Gn°) which is directly related with both molecular weight or percolation threshold in polymer and gels science respectively.