magnesium and-its-alloys, properties, structures, effect of alloying, applications

MAGNESIUM AND ITS ALLOYS Moiz Ullah Baig (MM-036), Saad Arif (MM-026), Haris Iqbal (MM-020) & Omar Siddiqi (MM-004)

Materials Engineering Department

INTRODUCTION

The word ‘Magnesium’ is derived from the Greek

word ‘Magnesia’. It is a white silvery metal, dis-

covered by Joseph Black in 1755 at Edinburgh,

England. It is the 6th most abundant element on

earth and about 2.4% of earth crust contains

magnesium.

PROPERTIES

Crystal

Structure:

Hexagonal

Closed Packed

Atomic Number: 12 Atomic Mass: 24.3

Configuration: [Ne] 3s2

Group: Alkaline Earth Metal

Melting Point:

651 °C

Boiling Point:

1100 °C

Density:

1.738 gm./cm3

Specific Gravity:

1.738

Burns in air with an intense white light,

produces a lot of heat.

Group:

II-A

Period:

III

APPLICATIONS

Aircraft parts

As desulfurizers

and deoxidizers

As anode in ship

hulls and ballast tanks

to protect from

corrosion

Automotive

parts

Bicycles and

sports goods

Laptops and

cellphones

Bohr’s Model

MAGNESIUM ALLOYS

Magnesium is the metal for the 21st century. Mg-alloys are being considered as one of the

most versatile material choices amongst the structural materials that exhibit both energy

efficiency and environmental benefits. Mg-based materials (alloys and composites) have

enormous and unlimited potential to replace aluminum, steel and structural plastics in

diverse industrial and commercial sectors. Magnesium alloys have a relatively high

strength-to-weight ratio, with some commercial alloys attaining strengths as high as 380

MPa. High energy absorption means good damping of noise and vibration, as well as

impact and dent resistance.

Mg– Zn Binary

Alloy

Mg-Al Binary

Alloy

Zinc renders

more solid solution

strengthening than an equal

atomic percent of other alloying

elements. They have a

strong age hardening

response. By these

advantages, high

strength alloys

can be developed.

EFFECT OF

ZIRCONIA

The addition of

Zirconia (Zr)

enhances the

homogeneity of

microstructure by

making grains round. As a

result more zinc can dissolve

and contribute positively

to the strength of

alloy.

Solubility: 6.2% at eutectic temperature i.e. 341 °C

Solubility: 12.6% at eutectic temperature i.e. 437 °C

It is one of

the oldest and most

commonly used alloys.

Addition of aluminum reduces

the grain sizes and makes

dendrites finer and more

developed. Aluminum

increase hardness,

strength and has

minor effect on

density.

EFFECT OF

STRONTIUM

The effects of

strontium (Sr) on

microstructure are

found to be very

apparent. Addition of Sr

makes lamellar structure which

are distributed along the grain

boundaries and make

better creep resistant

alloy.

JOINING OF ALLOYS

Magnesium and magnesium alloys may be joined

by most of the common fusion and mechanical

fastening methods. Fusion methods include,

Shielded-metal arc welding

Gas welding

Electric resistance seam and spot welding.

While mechanical fastening methods include,

Riveting

Bolting

Adhesive bonding.

ADVANTAGES

DISADVANTAGES

Good machinability

Good creep resistance to 120 °C

High thermal conductivity

Easily gas-shield arc-welded

High tendency to galvanic corrosion when

contact with dissimilar metals and electrolyte.

Difficult to deform by cold working

High Cost

REFERENCES Introduction to Physical Metallurgy 2nd Edition—Sidney H Avner

Materials and Process in Manufacturing 10th Edition—Paul DeGarrmo

http://www.totalmateria.com/Article78.htm

http://www.intlmag.org/magnesiumapps/overview.cfm

https://www.forging.org/design/47-magnesium-alloys

http://www.rsc.org/periodic-table/element/12/magnesium

http://www.hindawi.com/journals/jma/2014/704283

https://www.jstage.jst.go.jp/article/matertrans/49/6/49_MOV2007315

http://www.foundryworld.com/uploadfile/20094161419781

http://ir.lib.uwo.ca/etd/816/

https://researchspace.auckland.ac.nz/handle/2292/22223

Magnesium

alloys are in use

around the world

in a variety of

different applications.

It is preferred

material when

looking for weight

reduction without

compromising

overall

strength.