Mechanical Properties & Material ProcessingofMagnesium-Lithium Alloys
Ming-Tarng Yeh*, Ching-Tang Chang*, Jian-Yih Wang** and Hsin-Chih Lin**** AmLi Materials Technology Co. LTD., Taiwan** National Dong Hwa University, Department of Materials Science & Engineering*** National Taiwan University, Department of Materials Science & Engineering

AFLM-2012
November 9, 2012

AmLi Materials Technology Co. LTD. Taiwan---Specialized Manufacturing Company of Magnesium Alloys---Alloy Design, Melting & Casting, Extrusion & Rolling, Deep Drawing &Pressing, Heat Treatment, Surface Treatment, Product & Application

Partnership of AmLi for Research and Development--Chung-Shan Institute of Science & Technology--National Taiwan University / National Dong-Hwa University*--Huang-Chieh Metal Industry Co., Ltd.**--Fuji Light-Metal Company Ltd./ Nippon Kinzoku**** jywang@mail.ndhu.edu.tw/ sean-chiu@amlitech.com** howard_lee@wjgm.com.cn*** toksup@tokyosupply.com

Collaboration Topics

Alloy Design
Material Analysis

Material Processing
End-User Applications

AmLi Materials Technology Co., LTD., Taiwan

Introduction• Magnesium alloys are considered as potential candidates fornumerous applications, especially in transportation vehicles orlightweight sectors for 3C (computer, communication andconsumer electronic) products owing to the excellent
properties, such as low density, high specific strength, highdamping capacity and high recycle ability.

remote control aircraft

speaker diaphragm

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Mg-Li alloys• The Magnesium-Lithium (Mg-Li) alloys with Li contents
ranging from 5 to 11 mass% exhibit a dual-phase structure of
Mg-rich (α-hcp) and Li-rich (β-bcc) phases. This dual-phasestructure has excellent formability and extra-low density, but
exhibits a moderate mechanical strength and a poor corrosion
resistance.

αα+ββAmLi Materials Technology Co., LTD., Taiwan• In this presentation, a variety of Mg-Li alloys (LZ51-LZ121)
are prepared. Their densities are measured and compared toother light metals. The relationships between the chemicalcompositions, microstructures and mechanical properties forthese Mg-Li alloys are presented. Meanwhile, theimprovement of their mechanical properties and corrosion
resistance are also demonstrated.

AlloyDensity(g/cm3)

Mg

Li

1.74 0.53

LZ51--LZ121 AZ80 Al
1.60--1.431.80 2.7

Chemical compositions:
Li: 5~12 wt%
Zn:1 wt%
Mg: balanced

Mg-Li alloys are the lightest
structure metals for engineering
applications.

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Ti
4.5

Manufacturing Process of Mg-Li alloys
Material Processing
surfacetreatment

heat
treatment
Vacuum induction
melting and casting
physical andchemical
properties

extrusion, rolling,pressing, deep
drawing
corrosion
resistancedensitychemicalcomposition

microstructure

Alloy Design--component of vehicles--lightweight sectors for 3C
products

High Performance
Mg-Li Products

mechanicalproperty--speaker diaphragm--sports equipment--others

Material Analysis

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Manufacturing Process of Mg-Li alloys

AmLi Materials Technology Co., LTD., Taiwan• Microstructures of Casted Mg-Li alloys
LZ61

LZ101
ααββ

LZ71

LZ91

LZ71
LZ101
Alloyα/ββ ααββ

LZ51 LZ61 LZ71 LZ81 LZ91 LZ101 LZ121
97/3 82/18 64/36 46/54 32/68 16/840/100* The LZ51 alloy has a nearlyα phase, and the LZ121 exhibits a singleβphase.
With increasing Li content, moreβphase are formed.

AmLi Materials Technology Co., LTD., Taiwan• Microstructures of Annealed Mg-Li alloys
LZ61LZ91

LZ101 LZ121* Both α and β phases are elongated after rolling process.

• Effects of cold-rolling on the microstructures of LZ91 alloy(a) 10 %(b) 30 %(c) 50 %* After a severe cold rolling, the fine elongated α/β phases are formed.
AmLi Materials Technology Co., LTD., Taiwan

• Mechanical properties of Annealed Mg-Li alloys* The Mg-Li alloy with a high Li content has a low tensile strengthand a high elongation.
AmLi Materials Technology Co., LTD., Taiwan• Effects of cold-rolling on the mechanical properties of

LZ101 alloy

45°
90°

ND0°TDRD* The tensile strength increases, but fracture strain (elongation) decreases,
with increasing amount of cold rolling.

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Effects of aging precipitates on the mechanical properties of
LZ101 alloy
Tensile strength
Elongation

Solution-treated80250℃-aged

7060
Elongation [%]UTS, σ/MPa

As-extruded

220
RT-aged150℃-aged
200
180
160
140120100188MPa,
180MPa,50%
80130MPa, 48%
60 49%
402002 4 6 7 8S.T. 24 48 9672120144

5040173MPa,51%3020101 2 3 4 5

as-extruded

Aging time (hrs)

150 °C -6hrs

ββα

AmLi Materials Technology Co., LTD., Taiwan0• Corrosion Resistance--MAO (micro-arc oxidation)
Potentio-dynamic polarization curves
current density (Icorr.):
5.5x10-8 (Amps/cm2)
1.9x10-4 (Amps/cm2)

LZ91

Great !
LZ91

LZ91
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• Corrosion Resistance--sputter and Atomic Layer

Deposition (ALD)
Al2O3 film

ALD: layer-by-layer growth

Al interlayer

Substrate(a)(b)Surface morphologies of the LZ101 specimens. (a) the bare specimen, (b)the specimen with deposition of a dual-layer Al/Al2O3 film.
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Pt
Mg-Li

Al2O3CAl

ALD-Al2O3 film isamorphous

Al interlayer is acrystalline structure

Zone axis = [011]

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Potentio-dynamic polarization curves
BetterHigher potential (Ecorr.) and lower current density (Icorr.) indicate a better corrosion
resistance for Mg-Li alloys with deposition of a dual-layer Al/Al2O3 film.

AmLi Materials Technology Co., LTD., Taiwan

Summary
1. AmLi, focusing on light metal developments (density: 1.4~1.8g/cm3), has developed a series of Mg-Li alloys with designed
chemical compositions, densities, microstructures and mechanicalproperties.
2. The mechanical properties of Mg-Li alloys can be improved bythermal-mechanical treatments, such as fine-grain strengthening,
precipitation hardening, etc.
3. MAO and sputtering/ALD techniques can improve significantly
the corrosion resistance of Mg-Li alloys.
4. Mg-Li alloys having excellent mechanical properties andmanufacturability, can be considered as potential candidates fornumerous applications, especially in transportation vehicles orlightweight sectors for 3C products.
AmLi Materials Technology Co., LTD., Taiwan