Microstructural evolution and mechanical performance of cast Mg-3Nd-0.2Zn-0.5Zr alloy with Y additions |
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Affiliation: | 1. National 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;2. Shanghai Spaceflight Precision Machinery Institute, Shanghai 201600, China |
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Abstract: | This work investigated the effects of different Y additions (0, 1.5, 3.0 and 4.5 wt.%) on the microstructural evolution and mechanical performance of cast Mg-3Nd-0.2Zn-0.5Zr alloy. The results show that as the Y content increases, the key secondary phases in as-cast alloys change from the Mg12Nd type to the Mg24Y5 type. Meanwhile, the number density of Zn-Zr particles in the grains of as-quenched alloys gradually decreases. HAADF-STEM observations of peak-aged samples reveal that element Y is greatly enriched in the globular β′ precipitates, leading to a significantly increased volume fraction and promoted precipitation kinetics of β′ precipitates, resulting in enhanced strength of the alloy. Tensile tests reveal that, with the addition of 4.5 wt.% Y, the yield strength of the base alloy is substantially increased by 88 and 61 MPa after being aged at 200 and 225 °C under peak-aged conditions, respectively. |
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Keywords: | Mg-3Nd-0.2Zn-0.5Zr alloy Y alloying age-hardening response microstructural evolution mechanical properties |
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