Direct electrochemical reduction of low titanium chlorides into titanium aluminide alloy powders from molten eutectic KCl-LiCl-MgCl2

Titanium aluminides (Ti-Al) alloys are useful high-temperature structural materials for many industrial applications, but still limited by the long-cycle production and high-cost. In this study, a novel preparation process of Ti-Al alloys from low titanium chlorides (LTC) by electrochemical reduction was investigated. Cyclic voltammetry and square wave voltammetry were employed to evaluate the electrochemical behaviors of LTC in KCl-LiCl-MgCl2 melts. The data suggested that the reduction process of LTC at the cathode occurred through step by step: Ti3+ -> Ti2+, Al3+ -> Al, Ti2+/Al3+ -> Ti-Al alloy, and Ti2+ -> Ti. Inductively coupled plasma atomic emission spectrometry was utilized to determine the changes in Ti and Al ion concentrations during electrolysis of the melts on different anode materials. Using graphite anode, the data revealed a rapid decrease in both Ti and Al ions contents in the melts as the electrolysis time was prolonged. By comparison, the electrolysis system remained relatively stable using aluminum anode. The cathodic products using both graphite and aluminum anodes were then characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectrometry. As Al ion content declined in the melts using graphite rod anode, the cathodic products transformed from AlTi3 to Ti metal. By comparison, stable Al0.6Ti0.36 and AlTi3 were obtained when an aluminum rod was used as anode. (C) 2020 Elsevier Ltd. All rights reserved.