| Title |
Tailoring the α/β Phase Fraction and Mechanical Properties of Mg-Li Alloys via Combined Al and Bi Addition |
| Authors |
이병권(Byeong-Kwon Lee) ; 고은찬(Eun-chan Ko) ; 김용호(Yong-Ho Kim) ; 유효상(Hyo-Sang Yoo) ; 손현택(Hyeon-Taek Son) ; 김태훈(Tae-Hoon Kim) |
| DOI |
https://doi.org/10.3365/KJMM.2026.64.5.469 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
Extrusion; Mechanical properties; Mg-Li alloys; Microstructure; Phase fraction |
| Abstract |
In dual-phase Mg-Li alloy systems, achieving a balance between high strength and superior
ductility remains a critical challenge due to the inherent trade-off governed by the α-Mg and β-Li phases.
While aluminum (Al) is an effective strengthener, its addition typically stabilizes the hard α-Mg phase, leading
to a significant reduction in the ductile β-Li phase and consequent loss of formability. This study proposes
a novel alloying strategy utilizing bismuth (Bi) to mitigate Al-induced ductility loss through thermodynamic
phase control. The effects of combined Al (4, 6, 8 wt.%) and Bi (2 wt.%) additions on the microstructure and
mechanical properties of Mg-Li alloys were systematically investigated. The results demonstrate that Bi
exhibits a strong chemical affinity for Mg, preferentially forming thermally stable Mg3Bi2 precipitates.
Critically, this reaction preferentially consumes Mg atoms from the matrix, thereby shifting the
thermodynamic equilibrium toward the Li-rich side and restoring the volume fraction of the ductile β-Li phase.
Consequently, the Bi-added alloys exhibited a simultaneous improvement in yield strength, ultimate tensile
strength, and elongation compared to their Bi-free counterparts. Specifically, the optimized Mg-8Li-6Al-2Bi
alloy achieved a yield strength of 205.52MPa, an ultimate tensile strength of 250.2MPa, and an elongation
of 16.75%, demonstrating an exceptional strength-ductility balance. These findings suggest that modulating
the phase constitution via element-specific reactivity offers a promising pathway for designing highperformance
ultralight Mg alloys. |