Investigation on the Direct Purification of Intermetallic Compound via Zone Melting — Al2Cu as a Case Study

In recent years, IMCs have attracted increasingly attention due to the potential to become novel structural and functional materials. In order to achieve the circular economy and green sustainability of IMCs, purification is important. However, unlike general alloys, it is difficult to separate IMCs into single metals and synthesize them again. Currently, there are no systematic reports on impurity removal and recovery of IMCs products. Fractional crystallization techniques (e.g., ZM) are expected to purify IMCs by simplifying separation and re-synthesis steps. Herein, this work has demonstrated for the first time the feasibility and effectiveness of direct purification of IMCs by ZM, using Al2Cu as an example. The synthesis, as well as the phase stability and homogeneity of Al2Cu before and after ZM were firstly investigated. In the next step, the purification efficiency was optimized by studying the influencing factors. Moreover, the distribution coefficients of impurities, the crystal growth of Al2Cu and the migration behaviors of impurities were discussed. This work is intended to provide valuable guidance for the sustainable development of IMCs.