Microwave Irradiation Process for Al–Sc Alloy Production

Abstract

Scandium is being explored as an alloying element for aluminium alloys, which are gaining importance as high-performance lightweight structural alloys in the transportation industry. Sc-rich ScAlN thin films show strong piezoelectricity and can be fabricated on a hard substrate for use as wideband surface acoustic wave filters in next-generation wireless mobile communication systems. However, the use of ScAlN thin films in microelectromechanical system devices is limited by the high cost of metallic Sc, which is due to the difficulty in smelting of this material. Here, we propose a novel microwave irradiation process for producing Al-Sc alloys, with Mg ions as a reducing agent. Although scandium oxide is thermodynamically stable, intermetallic Al 3 Sc is obtained in high yield (69.8%) via a lowtemperature (660 °C) reduction reaction under microwave irradiation. Optical spectroscopy results and thermodynamic considerations suggest a non-thermal equilibrium reaction with the univalent magnesium ions excited by microwave irradiation.

Preparing Sc-Bearing Master Alloy Using Aluminum–Magnesium Thermoreduction Method

“…The arithmetic average of five points is the scandium content of the alloy ingots. The calculation formula of scandium recovery is shown in Equations (1) and (2). β = (βa + βb + βc + βd + βe)/5…”

“…The United States, Japan, Canada, Germany and other countries have also conducted much research on scandium aluminum alloy and made great achievements. The recent development of NASA Langley research center of the brand for aluminum C557, scandium-zirconium alloy using scandium and synergistic reinforcement effects, not only improves strength and thermal stability, but also enables the alloy to work at liquid hydrogen temperatures [1][2][3].…”

Mg Ion Plasma Generated by a High Magnetic Field in a Microwave Resonator

“…Similarly, scandium oxide was reduced at a low temperature of 660 • C using a multimode applicator and Mg as the reducing agent. In these reduction reactions, a reduction in the reaction temperature was observed, and it is proposed that Mg ions acted as the reducing agent in the microwave process [24]. In addition, the reduction of copper oxide by carbon was measured by thermogravimetry to determine its reduction reaction temperature, and a lower reaction temperature was observed, suggesting that Ar plasma contributed to the reaction [13].…”