1. Magnesium alloys are lightweight metals that are commonly used in applications that require strength and low weight, such as in aerospace and automotive components. 2. The major magnesium alloys include Mg-Al based alloys, Mg-Zn based alloys, and Mg-rare earth alloys. Mg-Al alloys like AZ31 and AZ61 provide good strength and ductility. Mg-Zn alloys like ZK51A offer high tensile strength. 3. Magnesium alloys can be joined using welding techniques like TIG welding and friction welding. They are easily die cast but require special considerations for corrosion resistance in engineering applications.

1. Microstructural features, properties
and application of magnesium alloy
Vinayak kumar
NIT-TRICHY
Industrial metallurgy

2. • Found 2.8% in sea water and other forms, i.e., dolomite (CaMg(CO3)2),
magnesite (MgCO3) and Carnallite (KMgCl3.6H2O).
• Magnesium with 99.8% purity are readily available but rarely used in
this stage for engineering applications.

3. Applications
phone bodies. Magnesium side panels
Alloyed wheel
Gearbox housing in the VW-
Passat
Aerospace applications
Cam and mobile

4. Physical properties of magnesium
• Low strength and toughness and corrosion
resistance.
• Easily flammable with oxygen.
• Alloyed with Al, Zn, Th, rare earth metals to produce alloys with high-
strength-to weight ratios.
• Tends to form compounds with negative valence ion (due to strong
electropositive) rather than solid solution.
• Not readily plastically deformed at room temperature due to HCP
structure.
• Cast magnesium alloys dominate 85-90% of all magnesium alloy products,
with Mg-Al-Zn system being the most widely used.
Crystal structure HCP a = 0.3202, c = 0.5199, c/a = 1.624
Atomic diameter 0.320 easily alloyed with Al, Zn, Ag, Zr
Density (g.cm-3) 1.74
Melting point (oC) 650

5. Classification of magnesium alloys
• ASTM system designated by two capital letter
followed by two or three numbers.
F – Iron
G – Magnesium
H – Thorium
K – Zirconium
L – Lithium
M - Manganese
N – Nickel
P – Lead
Q - Silver
R - Chromium
S – Silicon
T – Tin
Y –Antimony
Z - zinc
A – Aluminium
B – Bismuth
C – Copper
D – Cadmium
E – Rare earths
• The letters stand for the two major alloying elements
- first letter - the highest amount
- second letter - the second highest amount
• The numbers stand for the amount of the two major
alloying elements
- first number following the letters stands for
the wt% of the first letter element.
- second number stands for the wt% of the second
letter element.

6. Example
The magnesium alloy contains
2 wt% silver, 2% rare earths
and in the A modification.
T6 – solution heat-treated, quenched
and artificially aged.
QE22A-T6 -
AZ92A - The magnesium alloy contains
9 wt% aluminium, 2 wt% zinc.

7. Commercial magnesium alloys
•
•
•
•
•
Magnesium- Aluminum based alloys
Magnesium-Zinc based alloys
Magnesium-Rare Earth alloys
Magnesium-Thorium based alloy
High temperature Mg casting alloys

8. Mg-Al based alloy
• Al is alloyed to increase strength, castability and corrosion resistance
• Maximum solid solubility is ~ 12.7% at 818F
• Decreases to 3.2% at 400 F.

9. • This group includes Magnesium-Aluminum- Manganese and Magnesium- Aluminum- Zinc.
• AZ63A is used where maximum toughness along with moderately high yield strength.
• AZ92A is used where maximum yield strength plus good pressure-tightness are required.
• The microstructure of AZ92A alloy is shown
• The structure in sand-cast condition shows a network of massive δ (Mg17Al12)

10.  However most of the eutectic has separated, the ε phase has joined the
primary ε grains, leaving behind the compound as a white network.
 By rapid cooling and subsequently artificial aging can cause precipitation of
the compound as fine particle within the grain.

11.  The wrought alloy M1A (1.2% Mn) is low cost, low strength has excellent
weldability, corrosion resistance and hot formability.
 AZ31 with low calcium content(PE alloy) is widely used for magnesium
photoengraving sheet.
 AZ61A and AZ80A has good strength and ductility

12. Chemical composition of Mg-Al based
alloy and applications

13. Mechanical properties of Mg-Al based
alloys

14. Mg-Zn based alloys
 Essentially magnesium-zinc-zirconium (ZK) and magnesium-zinc-thorium
(ZH) casting alloys
 Zirconium is added for grain refinement so increases the mechanical
properties
 Zn controlling is important as it causes microporosity and hot cracks so
Thorium and rare-earth metal is added with effect on mechanical properties
 ZK51A, ZK61A,the highest tensile strength and ductility of any Mg casting
alloy

15. ZH62A-T5 Lamellar form of Eutectic Mg-Th-Zn
Mg rich solid
solution
Compound
of Mn-Th-
Zn

16. Chemical composition, application and
mechanical properties of Mg-Zn based alloy

17. Magnesium-Rare Earth-based alloys
 Includes of magnesium-rare earth-zirconium(EK), magnesium- rare earth-
zinc
 By addition of rare earth elements we get improvement in elevated-
temperature properties
 So these alloys are suitable for use up to 480˚C
Alloy EZ33A-T5 sand casing
Mg –E compound
Mg rich solid solution

18. Magnesium-thorium-based Alloys
 Includes magnesium-thorium-zirconium(HK) and magnesium-thorium-
zinc(HZ)
 Improved elevated temperature properties
 HK31A- short-time elevated temperature under high stress
 HZ32A –long-time lower stress applications

19. High temperature Magnesium casting alloys
 Primarily used for aerospace applications due to light weight (major consideration)
 Application range 200-250oC with tensile strength ~240MPa
 Mg-Ag-RE alloys
QE22-has been used for aerospace applications, i.e., landing wheels, gear box
housings.
 Mg-Y-RE alloys
 WE43-has been developed for improved elevated temperature tensile properties.
 Mg-Ag-Th-RE-Zr alloys

20. Forging of Mg alloys
Advantages of forged magnesium components compared to commonly
used die cast magnesium parts:
 Excellent strength, especially with the fibres lying parallel to the main
load direction.
 Very good properties for pressure-sealed components because of a
forging process in preventing a porous microstructure

22. Joining of magnesium alloys
 Arc welding ( TIG, MIG )
 Laser beam welding
 Electron beam welding
 Diffusion welding
 Friction welding
 Spot welding

23. Engineering design with Magnesium alloys
 Advantage
 Ability to die cast at high productivity rate
 Good creep resistance
 High damping capacity due to ability to absorb energy elastically
 High thermal conductivity permitting rapid heat dissipation
 Good machinability
 Easily gas-shield arc-welded
 Disadvantage
 High tendency to galvanic corrosion with dissimilar metals or electrolyte.
 Difficult to deform by cold working

24. Thank you