Effect of Ca Content on the Mechanical Properties and Corrosion Behaviors of Extruded Mg–7Li–3Al Alloys
Abstract
:1. Introduction
2. Experimental Procedures
3. Results
3.1. Microstructure
3.2. Mechanical Properties
3.3. Corrosion Behavior
3.4. Immersion Test
4. Discussion
4.1. Effect of Ca Content on the Strength of Extruded Mg–7Li–3Al–xCa Alloys
4.2. Corrosion Mechanism of the Extruded Mg–7Li–3Al–xCa Alloys
5. Conclusions
- (1)
- The grains of extruded Mg–7Li–3Al–xCa alloys were significantly refined as a result of dynamic recrystallization during the extrusion process. The α-Mg and β-Li phases were elongated along the extrusion direction. Al2Ca in the alloys formed and mainly distributed at the boundaries of the α-Mg and β-Li phases and at the grain boundaries.
- (2)
- With increasing Ca content, the strength of the extruded Mg–7Li–3Al–xCa alloys first increased and then decreased. The extruded Mg–7Li–3Al–0.4Ca alloy exhibited favorable mechanical performance, demonstrating a UTS of 286 MPa, a TYS of 249 MPa, and elongation of 18.7%. The extruded Mg–7Li–3Al–0.8Ca alloy exhibited favorable mechanical properties at 423 K (150 °C), with an UTS of 191 MPa.
- (3)
- The addition of Ca can improve the corrosion resistance of the extruded Mg–7Li–3Al alloy, which is attributed to the formation of Al2Ca particles. The corrosion mechanism of the extruded Mg–7Li–3Al alloy is local corrosion initiated at the phase boundaries, while for the extruded alloys containing Ca, the corrosion mechanism is pitting corrosion starting on the Al2Ca particles.
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Materials | Chemical Composition (wt.%) | |||
---|---|---|---|---|
Li | Al | Ca | Mg | |
Mg–7Li–3Al | 6.85 | 2.78 | - | Bal. |
Mg–7Li-3Al–0.4Ca | 7.21 | 2.85 | 0.38 | Bal. |
Mg–7Li-3Al–0.8Ca | 6.49 | 3.12 | 0.87 | Bal. |
Mg–7Li–3Al–1.2Ca | 6.76 | 2.75 | 1.15 | Bal. |
Position | Mg | Al | Ca |
---|---|---|---|
A | 61.12 | 38.88 | 0 |
B | 0 | 65.88 | 34.12 |
C | 75.44 | 16.67 | 7.89 |
D | 59.51 | 27.38 | 13.11 |
E | 0 | 51.46 | 48.54 |
F | 0 | 68.54 | 36.46 |
Extruded Alloys | TYS (MPa) | UTS (MPa) | Elongation (%) |
---|---|---|---|
Mg–7Li–3Al | 233 | 268 | 16.3 |
Mg–7Li–3Al–0.4Ca | 249 | 286 | 18.7 |
Mg–7Li–3Al–0.8Ca | 229 | 263 | 19.7 |
Mg–7Li–3Al–1.2Ca | 207 | 238 | 19.3 |
Extruded Alloys | TYS (MPa) | UTS (MPa) | Elongation (%) |
---|---|---|---|
Mg–7Li–3Al | 145 | 156 | 24.3 |
Mg–7Li–3Al–0.4Ca | 141 | 163 | 21.1 |
Mg–7Li–3Al–0.8Ca | 163 | 191 | 18.5 |
Mg–7Li–3Al–1.2Ca | 98 | 113 | 24.8 |
Alloys | Ecorr (V vs. SCE) | Eb (V vs. SCE) | βc (mV/dec) | icorr (μA/cm2) |
---|---|---|---|---|
Mg–7Li–3Al | −1.5445 | - | −342.18 | 134.90 |
Mg–7Li–3Al–0.4Ca | −1.48742 | - | −240.84 | 39.81 |
Mg–7Li–3Al–0.8Ca | −1.4940 | - | −294.18 | 63.10 |
Mg–7Li–3Al-1.2Ca | −1.4799 | −1.3735 | −260.61 | 31.62 |
Ca Content | RS (Ω) | Rct (Ω cm2) | CPE1 (10−6 sn Ω −1 cm−2) | n1 | Rf (Ω cm2) | CPE2 (sn Ω −1 cm−2) | n2 | L |
---|---|---|---|---|---|---|---|---|
0Ca | 17.09 | 257.7 | 26.556 | 0.87955 | 14.6 | 0.00614 | 0.60395 | 20.75 |
0.4Ca | 14.06 | 447.6 | 10.306 | 0.94147 | 235 | 0.00427 | 0.53179 | 231.9 |
0.8Ca | 20.65 | 401.7 | 14.27 | 0.92142 | 189.1 | 0.00472 | 0.66559 | - |
1.2Ca | 15.32 | 475.1 | 11.27 | 0.93109 | 241.4 | 0.00649 | 0.60237 | 140.6 |
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Xiong, X.; Yang, Y.; Deng, H.; Li, M.; Li, J.; Wei, G.; Peng, X. Effect of Ca Content on the Mechanical Properties and Corrosion Behaviors of Extruded Mg–7Li–3Al Alloys. Metals 2019, 9, 1212. https://doi.org/10.3390/met9111212
Xiong X, Yang Y, Deng H, Li M, Li J, Wei G, Peng X. Effect of Ca Content on the Mechanical Properties and Corrosion Behaviors of Extruded Mg–7Li–3Al Alloys. Metals. 2019; 9(11):1212. https://doi.org/10.3390/met9111212
Chicago/Turabian StyleXiong, Xiaoming, Yan Yang, Hongju Deng, Minmin Li, Jinguang Li, Guobing Wei, and Xiaodong Peng. 2019. "Effect of Ca Content on the Mechanical Properties and Corrosion Behaviors of Extruded Mg–7Li–3Al Alloys" Metals 9, no. 11: 1212. https://doi.org/10.3390/met9111212