Quasi-superplasticity in an Mg–Li–Al–Y alloy processed by rolling
In order to explore the high temperature ductility of ultra-light magnesium-lithium alloy, a new Mg-7.28Li-2.19Al-0.091Y (LAY720) alloy was prepared by casting and rolling. The microstructural evolution, mechanical properties, model, and deformation mechanism under hot tension were studied by optica...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-01-01
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| Series: | Journal of Materials Research and Technology |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2238785424030564 |
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| Summary: | In order to explore the high temperature ductility of ultra-light magnesium-lithium alloy, a new Mg-7.28Li-2.19Al-0.091Y (LAY720) alloy was prepared by casting and rolling. The microstructural evolution, mechanical properties, model, and deformation mechanism under hot tension were studied by optical microscope, X-ray diffraction, scanning electron microscope, energy dispersive spectroscopy, and tensile tester. Mechanical properties tests showed that the maximum elongation of 265.8% was achieved at 623 K and 5.0 × 10−4 s−1 Microstructural examination found that the tensile alloy is composed of α-Mg + β–Li dual-phase banded grains under high strain rate condition, which disappears when the strain rate decreases and the temperature increases. Continuous dynamic recrystallization occurs at 473 and 523 K while dynamic grain growth occurs at 573 and 623 K under the other strain rates. The AlLi compound precipitation at the α-Mg grain boundary was discovered in LAY720 alloy at 523 K and 1.67 × 10−4 s−1. A critical strain and critical stress model for dynamic recrystallization of the alloy was obtained. Discontinuous dynamic recrystallization and dynamic grain growth were estimated by our models. A power-law constitutive analysis revealed that the stress exponent of 3 and the deformation activation energy of 138.35 kJ/mol confirmed that lattice diffusion controlled dislocation glide and dynamic grain growth are the deformation mechanism at 623 K and 5.0 × 10−4 s−1. |
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| ISSN: | 2238-7854 |