About the Mg and its alloys when they mixed up how the changes microstructure and their properties

1. MAGNESIUM AND ITS ALLOYS
-MANISIVARAJA I
MME

2. OBJECTIVE:
1. Discovery
2. Atomic structure
3. Properties
4. Pase diagrams of Mg-Al and Mg-Zn
5. Micro structure anaysis
6. Corrosion behaviour
7. Applications
8. Conclusion and Future scope

3. • In 1755
• By Joseph Black
• At Edinburgh, England
• Name derived from Greek word ‘Magnesia’
• About 2.4% of the Earth’s crust contains Magnesium it the 6th
most abundant element.
DISCOVERY

4. ATOMIC STRUCTURE
Symbol - Mg
Atomic number - 12
Atomic mass - 24
Density - 1.738 g/cm3
Group: Alkaline Earth Metal
Configuration: 1s2, 2s2, 2p6, 3s2
Melting point: 650 C
Boiling point: 1,092 C

5.  Low density
 High specific strength
 Stiffness
 Good damping performance
 Good biocompatibility
 Large hydrogen storage capacity
 High theoretical specific capacity for battery, etc.
Properties:

6. • Mg-Al casting alloys
• Mg-Al-Sr casting alloys
• Mg-Zn casting alloys
• Mg-Zn-Zr casting alloy
• High temperature Mg casting alloys
Commercial magnesium alloys

7. MAGNESIUM-ALUMINUM BINARY PHASE
DIAGRAM

8. SCHEMATIC VIEW OF EUTECTIC MICROSTRUCTURE
OF MG-AL ALLOY
• Primary α-Mg
Pure Mg Dendrites
• Intermetallic phase β-
phase i.e. Mg17Al12

9. (a) Mg-1%Al (b) Mg-5%Al (c) Mg-6%Al (d) Mg-9%Al
Grain sizes of binary Mg-Al Alloys
MAGNESIUM-ALUMINUM GRAIN SIZES
Reduces grain size and improves ultimate tensile and yield strength

10. EFFECT OF STRONTIUM ADDITION
• Distributed along the grain boundaries
• Lamellar structure formed
• Better creep resistance can be obtained
SEM photos of the as-cast alloys

11. SEM photos of the Mg-Al-Sr as-cast alloys

12. MAGNESIUM-ZINC BINARY PHASE DIAGRAM

13. Grain sizes of binary Mg-Zn alloys, (a) 0.2 at.%, (b) 0.7 at.%
MAGNESIUM ZINC GRAIN SIZES
 Reduces with increase in concentration of Zinc (Zn)

14. EFFECT OF ZIRCONIAADDITION ON GRAIN SIZE
• Enhances the homogeneity by making the grains round
• Reducing the amount of eutectic at the grain boundaries
• Contribute positively to the strength of the alloy

15. COMBIINATION OF MATERIALS PROPRTIES DELIVERIED
Mg-Al Increase strength, castability and slightly increase in density
Light weight and superior ductility
Mg-Al-Sr Creep resistance
Mg-Al-Zn Increases strength by solid solutionstrengthening and
precipitation hardening.
Mg-Zn Increases the alloys fluidity in casting.
Improve corrosion resistance
Mg-Ag-RE Increase in wear resistance
Outstanding age-hardening response.
Good tensile properties up to 200oC.
Mg-Y-RE Improved elevated temperature
tensile properties.
Mg-Ag-Th-RE-Zr Improve high temperature properties

16. CORROSION BEHAVIOUR OF Mg ALLOYS
• Lightest structure materials with high chemical activity.
•Standard potential of pure Mg E0 = -2.4
•Oxide film of magnesium are not stable in solution with pH<10.5.
•Magnesium always used as a sacrificial anode
•Mg and its alloys exhibit the special features of Negative Difference Effect
(NDE) and “anodic hydrogen evolution” . The hydrogen evolution
reaction will be accelerated with increasing anodic potentials.

17. Potentiodynamic curves of Mg-2Zn and Mg-5Zn:

18. 1) The effect of hydrogen on the corrosion resistance of the Mg-2Zn and Mg-5Zn
alloys are investigated by charging hydrogen treatment of the both alloys at the
cathodic currentsof -1, -5 and -10 mA.
2) The compact oxide films can be observed on the samples after charging hydrogen
treatment, and the coverage percents of the films increase with the increase of
charging hydrogen currents.
3) Especially the Mg-5Zn exhibits a faster film growth rate.
4) The corrosion resistance of the Mg-2Zn alloy is improved with increasing
cathodic charging hydrogen currents from -1 to -10 mA
5) Mg-5Zn alloy presents the best corrosion resistance at the charging hydrogen
current of -5 mA.

19. Applications in Aerospace industry:

20. AUTOMOTIVE INDUSTRY:

21. Mg applications in other major domains:

22. Conclusion and Future scope:
1. By addition of other alloying materials to Mg the grain size get decreasese
though it can exhibit excellent properties
2. High-temperature magnesium casting alloys shows good creep resistance
to 120oC and corrosion resistance
3. Due to Mg is a light weight structural materal it shows anormous applications in
the multiple sectors like aerospace, automotive, sports, internal casings,missiles
etc..,
4. Large hydrogen storage capacity
5. High theoretical specific capacity of Mg showa interest on developing batteries,
etc

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Sci.Eng. C 2014, 39, 330–335. [CrossRef] [PubMed]
4. Gu, X.N.; Zheng, Y.F. A review on magnesium alloys as biodegradable materials. Front. Mater.
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5. Witte, F.; Kaese, V.; Haferkamp, H.; Switzer, E.; Meyer-Lindenberg, A.; Wirth, C.J.; Windhagen,
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[CrossRef] [PubMed]A. Atrens, G.L. Song, F.Y. Cao, Z.M. Shi, P.K. Bowen, J. Magnesium
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REFERENCES:

24. THANK YOU