Effect of complex melt-refining treatment on microstructure and mechanical properties of sand-cast Mg–10Gd–3Y–0.5Zr alloy
(1. National Engineering Research Center of Light Alloys Net Forming and State Key Laboratory of
Metal Matrix Composite, Shanghai Jiao Tong University, Shanghai 200240, China;
2. Shanghai Light Alloy Net Forming National Engineering Research Center Co., Ltd., Shanghai 201615, China;
3. Shanghai Aviation Precision Machinery Research Institute, Shanghai 201600, China)
Metal Matrix Composite, Shanghai Jiao Tong University, Shanghai 200240, China;
2. Shanghai Light Alloy Net Forming National Engineering Research Center Co., Ltd., Shanghai 201615, China;
3. Shanghai Aviation Precision Machinery Research Institute, Shanghai 201600, China)
Abstract: The effect of complex melt-refining treatment (melt flux incorporating with rotating gas bubble stirring) on microstructure and mechanical behavior of the sand-cast Mg-10Gd-3Y-0.5Zr alloy was investigated. In addition, the melt purifying mechanism of the complex melt-refining treatment for the sand-cast alloy was discussed systematically. The results show that the new melt-refining method can significantly improve melt quality and mechanical behavior of the tested alloy, i.e., compared to the reference unpurified alloy, the volume fraction of inclusions decreased from 0.47% to 0.28%, the ultimate tensile strength and elongation for T6-treated alloy increased from 245 MPa and 0.7% to 312 MPa and 4.5%, respectively. Especially, combining 1% flux with rotating gas bubble stirring can get even better purifying effectiveness than conventional sole 2% flux purification; the use of melt flux decreased by 50% and significantly reduced environmental pollution.
Key words: magnesium alloy; sand-cast; purification; complex melt-refining; mechanical property