This document discusses various metal alloys, including their compositions, properties, designations, and applications. It covers aluminium alloys, magnesium alloys, nickel alloys, titanium alloys, and copper alloys. Key points include the lightweight and corrosion resistant properties of aluminium alloys, magnesium alloys having higher strength to density than aluminium but poorer ductility, nickel alloys being used in gas turbine blades due to high strength and corrosion resistance at high temperatures, and copper alloys having high conductivity.

1. Aluminium alloys
• Aluminium has many attractive properties
• Lightness
• Resistance to corrosion
• High strength to weight ratio
• High reflectivity
• Excellent workability
• High electrical and thermal conductivity
• High elasticity making it suitable for shock load
conditions
• Toughness at low temperature-a property in which steel
is comparatively poorer

2. • Containing small percentage of other
metals- to provide strength, toughness and
other properties
• Other metals have limited solubility in it
• Aluminium alloy designation
• 1XXX- 99.00 percent aluminium
• Last two digit- minimum percentage of
aluminium in hundredths
• Second digit from left- special control of
given number of impurities present
• First digit alloy type

3. • Aluminium alloys fall in to two general
categories: heat treatable, non-heat
treatable
• 2000,5000,6000,and 7000 series may be
strengthened by heat treatment
• 3000, 4000-non heat treatable

4. • 1xxx-pure aluminium- excellent electrical and
thermal conductivity and resistant to
atmospheric corrosion
• 2XXX- respond to heat treatment- 2024-aircraft
alloy-poor corrosion resistance- surface cladding
with high purity aluminium or 6XXXAl-alloy
• 3003-(Mn 1-1.5%)- good corrosion resistance,
response to welding, cold workability
• Major applications are: tubes, washing machine,
cooking range etc

5. • 4XXX- non-heat treatable- Mg promotes
strengthening
• Excellent cryogenic properties in addition
to good response to welding
• Good resistance to saline water and
marine atmosphere
• 6XXX-normally used for extrusion-good
corrosion resistance
• Applications: structural frames, gears,
pipes

6. • 7XXX-heat treatable-possesses highest
mechanical properties
• Smaller addition of copper and chromium
improves the mechanical properties
• 7075 used n aerospace, making sports
good, nuts and bolts
• Alloying lithium to aluminium decreases
density, increases the modulus due to
formation of Al3Li

7. Use of second-generation AlLi alloys (8090 variants) on the AgustaWestland
EH101 (Pasang et al., 2012).

9. Aloha airlines Boeing Fuselage failures (1988)
On April 28, 1988 an Aloha airlines Boeing 737 (19 year old – design life 20 years
) had its fuselage ripped off in mid air at 24,000 ft but landed safely with one
causality reported.
A major portion of the upper crown skin and structure separated in flight causing
an explosive decompression of the cabin
Opened up accelerated aging of structures due to corrosion
Corrosion failures are environmentally sensitive. The fuselage was primarily made of Aluminum. It is a
thermodynamically reactive metal. However, a 1 nano-meter oxide film is typically formed for corrosion
prevention. In a near neutral environment as the one in Hawaii (PH 8-8.3), uniform corrosion that requires
high acidic or alkaline media was ruled out. However, pitting corrosion can still take place. Pitting corrosion
occurs when the metal is put into permanent or intermittent contact with aqueous media. It is known to
develop with chloride ions. The operating environment of Aloha airline flight 243 had a relatively high
salinity, indicating high concentration of chloride.

18. Magnesium alloys
• Magnesium having a hexagonal structure,
possesses limited ductility.
• More difficult to deform it to shape,
requiring higher temperature to enhance
its deformability
• Higher strength to density ratio than Al
• Mg alloys have poor wear resistance and
low fatigue resistance

19. • ASTM designation- four part system
• First part-two code letters- indicates the
two main alloys- the first letter indicates
the alloy with higher percentage- second
with next higher percentage
• A-Aluminum: B-Bismuth; C-Copper; D –
Cadmium; E- rare earth; F-Iron; H-
Thorium; K-Zirconium; L- Beryllium; M-
Manganese; N-Nickel; P-Lead; Q-Silver;
S-Silicon; T-Tin; Z-Zinc

20. • The second part consists of two numbers
corresponding to the rounded of percentages to
the nearest whole number of the two principal
alloys
• AZ92A
• The fourth part consisting of a letter and a
number the temper heat treatment
• O-annealed; F-as fabricated; H- Strain
hardened; W- Unstable followed by solution heat
treatment
• T-Heat treated

21. • Mg-Al based alloy
AZ63A-max toughness, ductility-high
strength
AZ91A and AZ91B-for die casting
AZ31-general purpose extrusion alloy-not
heat treatable –strain hardening
AZ80A-heat treatable-excellent combination
of high strength and moderate elongation

22. Mg-Zn based alloys
• Zirconium is added-eliminates course
grained columnar cast structure
• ZK51A,ZK61A-high strength and ductility

28. Nickel alloys
• Ni has good corrosion resistance
• Ni chrome (80/20 Ni/Cr) is used for heaters
• Magnetic properties are very good e.g
Permalloy
• (Ni+ Fe, Cr, Mo) has high permeability and low
saturation
• Invar(Fe/35 Ni) which has almost zero thermal
expansion
• Used for metrology standards , pendulums,
balance wheels

29. • Nickel based super alloys- used in Gas
turbine blades
• Nimonics (Ni/Cr/Al/ti/Fe) and
Inconels(Ni/Cr/Fe) both with small
amounts of C, Co, Mo, W
• Solid solution ally precipitation hardened
with Ni3(Al,Ti)

32. Titanium alloys
• Titanium exists in two states: the low
temperature  phase and high
temperature  phase
• HCP structure
• C/a ratio 1.58 stable below 883 deg C nd
high temperature  phase stable above
this temperature and has BCC structure
• Under rapid cooling undergoes martensitic
transfermation

37. Copper alloys
High conductivity-corrosion resistance
Small addition of Ag, Cd, Cr-retain high conductivity-higher softening temperature
Beryllium copper (2%Be) precipitation gives higher strength but poorer conductivity
Brass
Cu/2%Zn-cap copper
Cu/5-15%Zn- gliding metals
Cu/30%Zn-70/30 or Cartridge Brass
Muntz metal-60/40 brass-sheathing,
condenser end plates-forgings-castings
Bronzes
Cu/9 Al- corrosion resistance
α-borozes: Cu-8%Sn
Phosphor bronze:Cu-8%Sn-0.5%p
Gunmetal:88Cu/10Sn/2Zn
Cu and Nickel-Solid Solution-80Cu/20Ni-Monel:Cu/30%Ni/0.1Fe,Mn