J. Mater. Sci. Technol. ›› 2024, Vol. 173: 202-217.DOI: 10.1016/j.jmst.2023.05.080

• Research Article • Previous Articles     Next Articles

Realizing the purification and grain refinement of Mg-Gd-Y alloy by one-step flux refining

Xin Tonga, Guohua Wua,*, Ming Sunb, Qiman Wanga, Liang Zhanga,*, Wencai Liua   

  1. aNational Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China;
    bSchool of Materials and Chemistry, University of Shanghai for Science and Technology, Shanghai 200093, China
  • Received:2023-03-23 Revised:2023-05-04 Accepted:2023-05-17 Published:2024-02-20 Online:2023-08-15
  • Contact: *E-mail addresses: ghwu@sjtu.edu.cn (G. Wu), liangzhang08@163.com (L. Zhang).

Abstract: In the conventional melt preparation of magnesium rare-earth (Mg-RE) alloys, the repeated heating/cooling process involved in grain refinement and flux refining usually prolongs the preparation period and aggravates melt oxidation. In this work, the purification and grain refinement of Mg-9Gd-3Y (GW93) alloy was simultaneously realized by one-step refining at 740 °C by using a self-developed compound flux. The results show that, only after holding for 10 min, the inclusion content of the alloy is reduced by 81% to 0.29%, while the grain size is reduced by 84% to 119 μm. A physical model depicting the interactions between compound flux and alloy melt was proposed based on thermodynamic calculation and microstructure observation. The grain refinement mechanism has been analyzed by considering the presence of Zr particle (Zrp) and Zr solute (Zrs). In addition, the generated RECl3 was found to be readily absorbed by the flux, decreasing the surface tension and promoting the purification efficacy of the flux, which plays an important role in the promoted elongation of the as-cast Mg-9Gd-3Y-0.5Zr (GW93K) alloy. This work presents a unique prospect in simplifying the melt preparation of Mg-RE alloy with a promoted quality.

Key words: Mg-Gd-Y-Zr alloy, Purification, Grain refinement, Compound flux, Settling behavior