摘要
The thermodynamic characterization as well as the rheological characterization of the A201 alloy were conducted.Thermodynamic simulations (CALPHAD method) and calorimetric experiments were performed to determine the solidus and liquidus temperatures, the melting range and the sensitivity of the solid fraction at the thixoforming temperatures.The rheology of aluminium alloy A201 was examined using a high temperature Searle rheometer.The flow behaviour was analyzed with concentric cylinders of graphite to avoid chemical interactions with the liquid or semi-solid aluminium.The rotational body was grooved to prevent a phenomenon called wall slippage.Continuous cooling experiment was used to observe the shear rate effects on the flow behaviour.It can be seen that the viscosity level decreases at higher shear rates.Shear rate jump experiment was carried out to evaluate the steady state flow curve within the analyzed shear rate range from 60 s-1 to 260 s-1.It is found that the power law indexes are-1.35 and-1.49 for 35% and 45% solid fraction, respectively.Finally, some mechanical property data of as-cast and as-thixoformed A201 alloy are included indicating the potential for high strength applications.
The thermodynamic characterization as well as the rheological characterization of the A201 alloy were conducted. Thermodynamic simulations （CALPHAD method） and calorimetric experiments were performed to determine the solidus and liquidus temperatures, the melting range and the sensitivity of the solid fraction at the thixoforming temperatures. The rheology of aluminium alloy A201 was examined using a high temperature Searle rheometer. The flow behaviour was analyzed with concentric cylinders of graphite to avoid chemical interactions with the liquid or semi-solid aluminium. The rotational body was grooved to prevent a phenomenon called wall slippage. Continuous cooling experiment was used to observe the shear rate effects on the flow behaviour. It can be seen that the viscosity level decreases at higher shear rates. Shear rate jump experiment was carried out to evaluate the steady state flow curve within the analyzed shear rate range from 60 s^-1 to 260 s^-1. It is found that the power law indexes are -1.35 and -1.49 for 35% and 45% solid fraction, respectively. Finally, some mechanical property data of as-cast and as-thixoformed A201 alloy are included indicating the potential for high strength applications.
基金
the "Ministerio de Ciencia e Innovación" and to the "Fondos FEDER",project "Integrauto" PSE-370000-2008-03
the Basque Government,project "ETORTEK, Manufacturing 0.0 II",for their financial support
