Characterization of rapidly solidified Al-Mg-Sc alloys with Li addition


This paper investigate the thermophysical properties of the liquid as well as the rapid solidification of Al5.0Mg0.2Sc alloys with 3.0 and 6.0 Li wt% by the discharge crucible, and Impulse Atomization techniques respectively. The discharge crucible method, allowed a simultaneous determination of density, surface tension and viscosity as a function of the temperature. While the density and surface tension are found to decrease with Li content, the viscosity increases due to short-range ordering occurring in intermetallic phases. In order to determine their characteristic temperatures, the alloys powder generated by Impulse Atomization were investigated using a Differential Scanning Calorimeter, while microstructural observations and chemical analyses were conducted using scanning and transmission electron microscopy with energy dispersive X-ray spectroscopy. To study the influence of Li on the microstructural phase formation in these alloys, diffraction patterns analyses in transmission electron microscopy, as well X-ray diffraction using synchrotron measurements were carried out. The conducted measurements and microstructure observations revealed the precipitations of Al3Sc and Al2MgLi phases in both alloy compositions. In addition, AlLi precipitates were observed in Al5.0Mg0.2Sc6.0Li alloy, which is in agreement with the phase diagram.
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