Effect of heat treatment on microstructure and mechanical properties of Mg<sub>97.5</sub>Gd<sub>1.9</sub>Zn<sub>0.6</sub> alloy
A ternary alloy strengthened by the phase with long period stacking ordered (LPSO) structure with composition of Mg<sub>97.5</sub>Gd<sub>1.9</sub>Zn<sub>0.6</sub> (atom fraction/%) was prepared by conventional permanent mold casting. The microstructure evolution a...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | zho |
| Published: |
Journal of Materials Engineering
2020-09-01
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| Series: | Cailiao gongcheng |
| Subjects: | |
| Online Access: | http://jme.biam.ac.cn/CN/10.11868/j.issn.1001-4381.2019.000716 |
| Summary: | A ternary alloy strengthened by the phase with long period stacking ordered (LPSO) structure with composition of Mg<sub>97.5</sub>Gd<sub>1.9</sub>Zn<sub>0.6</sub> (atom fraction/%) was prepared by conventional permanent mold casting. The microstructure evolution and mechanical properties in as-cast, as-annealed, as-extruded and extruded-T5 alloy were systematically investigated by OM,SEM,TEM and electronic universal testing machine. The results show that the as-cast microstructure of the alloy consists of the α-Mg matrix, (Mg,Zn)<sub>3</sub>Gd eutectic and lamellar 14H-LPSO phase. Annealing at 510℃ results in the transformation of (Mg,Zn)<sub>3</sub>Gd into the block-shaped 14H-LPSO phase. According to the distribution and morphology of the 14H-LPSO phase observed in the microstructure after annealing, the peritectoid transformation (Mg,Zn)<sub>3</sub>Gd +α-Mg→14H-LPSO possibly occurs during annealing. The lamellar 14H-LPSO and β' <sub>p</sub> precipitates have also been observed in the alloy during extruded-T5 treatment. Under the combined action of 14H-LPSO toughening and precipitation strengthening, the aged sample shows the best tensile properties at room temperature:ultimate tensile strength of 361 MPa, yield strength of 216 MPa and elongation of 6.9%. |
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| ISSN: | 1001-4381 1001-4381 |