Duralumin It is an important and interesting wrought alloy.

Its composition is as follows:

Copper = 3.5 – 4.5%; Manganese = 0.4 – 0.7%;Magnesium = 0.4 – 0.7%, and the remainder isaluminium.

This alloy possesses maximum tensile strength (upto400 MPa) after heat treatment and age hardening.After working, if the metal is allowed to age for 3 or 4days, it will be hardened. This phenomenon is knownas age hardening.

It is widely used in wrought conditions for forging,stamping, bars, sheets, tubes and rivets.

IES-1993Duralumin Alloy contains aluminium and copper in the ratio of

%Al %Cu

(a) 94 4

(b) 90 8

(c) 88 10

(d) 86 12

IES-1992Which of the following statement is incorrect about duralumin?

(a) It is prone to age hardening

(b) It can be forged

(c) It has good machining properties

(d) It is lighter than pure aluminium

Magnalium

It is made by melting the aluminium with 2 to 10%magnesium in a vacuum and then cooling it in avacuum or under a pressure of 100 to 200 atmospheres.

It also contains about 1.75% copper. Due to its lightweight and good mechanical properties, it is mainlyused for aircraft and automobile components.

Hindalium

It is an alloy of aluminium and magnesium with a small quantity of chromium.

Copper-zinc alloys (Brass)

The most widely used copper-zinc alloy is brass.

There are various types of brasses, depending upon theproportions of copper and zinc.

This is fundamentally a binary alloy of copper withzinc each 50%.

By adding small quantities of other elements, theproperties of brass may be greatly changed.

Applications of Cu alloys include: costume jewellery, coins, musical instruments, electronics, springs, bushes, surgical and dental instruments, radiators, etc.

Contd…

The addition of zinc strengthens the material andincidentally changes the colour to a yellow or goldeffect.

The ratio of copper and zinc can be varied foradvantages and the addition of other elements givesstill more variety of combinations of properties such asmachinability, strength, hardness, ductility (hot orcold), conductivity and corrosion resistance as well asmany others.

Lead additions are used to improve machinability. The lead is insoluble in the solid brass and segregates as small globules that help the swarf to break up in to small pieces and may also help to lubricate the cutting tool action.

IES-1992Addition of which of the following improves machining of copper?

(a) Sulphur

(b) Vanadium

(c) Tin

(d) Zinc

IES-1992Cartridge brass can be

(a) Cold rolled into sheets

(b) Drawn into wires

(c) Formed into tubes

(d) Any of the above.

Copper-tin alloys (Bronze) The alloys of copper and tin are usually termed as

bronzes.

The useful range of composition is 75 to 95% copperand 5 to 25% tin.

The metal is comparatively hard, resists surface wearand can be shaped or rolled into wires, rods and sheetsvery easily.

In corrosion resistant properties, bronzes are superiorto brasses.

Contd…

The hardness and strength of bronze increase with anincrease in tin content.

The ductility is also reduced with the increase in tinpercentage above 5.

When aluminium is also added (4 to 11%), theresulting alloy is termed aluminium bronze, whichhas a considerably higher corrosion resistance.

Bronzes are comparatively costly compared to brassesdue to the presence of tin which is an expensive metal.

The colour of aluminium bronze is similar to that of22 carat gold and it is frequently called ‘imitationgold’.

IES 2011Aluminium Bronze is also known as :

(a) Muntz metal

(b) White metal

(c) Duraluminium

(d) Imitation gold

Phosphor bronze When bronze contains phosphorus, it is called

phosphor bronze.

Phosphorus increases the strength, ductility andsoundness of castings.

This alloy possesses good wearing qualities and highelasticity.

A common type of phosphor bronze has the followingcomposition according to Indian standards Copper =87–90%, Tin = 9–10%, and Phosphorus = 0.1–3%.

The material is specified for pump parts, gears,springs, power screw nuts and bearings.

IES-2006In case of power screws, what is the combination of materials used for the screw and the nut?

(a) Cast iron screw and mild steel nut

(b) Carbon steel screw and phosphor bronze nut

(c) Cast iron screw and cast iron nut

(d) Aluminium screw and alloy steel nut

IES-1992The percentage of phosphorous in phosphor bronze

is

(a) 0.1 (b) 1

(c) 11.1 (d) 98

Gun Metal It is an alloy of copper, tin and zinc.

It usually contains 88% copper, 10% tin and 2% zinc.

This metal is also known as Admiralty gun metal.

The zinc is added to clean the metal and to increase itsfluidity.

It is not suitable for being worked in the cold state butmay be forged when at about 600°C.

It is extensively used for casting boiler fittings, bushes,bearings, glands, etc.

IES-2003Gunmetal, which is used in journal bearings, contains

(a) 88% Cu, 10% Sn, 2% Zn

(b) 80% Cu, 10% Zn, 10% Al

(c) 85% Cu, 5% Mg, 10% Al

(d) 85% Cu, 5% Sn, 10% Pb

IES-1994Which of the following pairs are correctly matched?

1. Silicon steels ………Transformer stampings

2. Duralumin ……Cooking utensils.

3. Gun metal................. Bearings

Select the correct answer using the codes given below.

Codes:

(a) 1, 2 and 3 (b) 1 and 2

(c) 1 and 3 (d) 2 and 3

IES 2011Match List –I with List –II and select the correct answer using the code given below the lists :

Codes

A B C D A B C D

(a) 3 1 2 4 (b) 4 1 2 3

(c) 3 2 1 4 (d) 4 2 1 3

List –I List –II

A. Gun Metal 1. Worm wheel

B. Phosphor bronze 2. Cylinder block

C. Gray cast iron 3. Piston

D. Al alloy 4. Bushings

Monel metal It is an important alloy of nickel and copper.

It contains 68% nickel, 29% copper and 3% otherconstituents like iron, manganese, silicon and carbon.It is superior to brass and bronze in corrosion resistingproperties.

It is used for making propellers, pump fittings,condenser tubes, steam turbine blades, sea waterexposed parts, tanks and chemical and food handlingplants.

IES 2011Admirality Brass is used for

(a) Condenser Tubes

(b) Rivets

(c) Piston rods

(d) Utensils

IES-2006Match List-I (Composition) with List-II (Application) and select the correct answer using the code given below the Lists:List- I List -IIA. Commercial bronze (10% Zn) 1. RadiatorB. Red brass (15% Zn) 2. Spring metalC. Aluminium brass ( 22% Zn, 2% Al) 3. Forging and

stampingD. P-bronze (11 % tin) small amount of P) 4. Power plant

and chemical equipment

Codes: A B C D A B C D(a) 2 4 1 3 (b) 3 1 4 2(c) 2 1 4 3 (d) 3 4 1 2

IES-2003Monel metal is an alloy of

(a) Iron and carbon

(b) Copper and zinc

(c) Aluminium and copper

(d) Copper and nickel

IES-2004Match List I (Alloy) with List II (Application) and select the correct answer using the codes given below the Lists:

List I List II

A. Silicon steel 1. Marine bearings

B. High carbon steel 2. Cutting tools

C. High speed steel 3. Springs

D. Monel metal 4. Transformer laminations

Codes:A B C D A B C D

(a) 1 2 3 4 (b) 4 3 2 1

(c) 4 2 3 1 (d) 1 3 2 4

Inconel It consists of 80% nickel, 14% chromium, and 6% iron.

This alloy has excellent mechanical properties atordinary and elevated temperatures.

It can be cast, rolled and cold drawn.

It is used for making springs which have to withstandhigh temperatures and are exposed to corrosive action.

It is also used for exhaust manifolds of aircraft engines.

Nichrome

It consists of 65% nickel, 15% chromium and 20% iron.

It has high heat and oxidation resistance.

It is used in making electrical resistance wire forelectric furnaces and heating elements.

Nimonic It consists of 80% nickel and 20% chromium.

It has high strength and ability to operate underintermittent heating and cooling conditions.

It is widely used in gas turbine engines.

Babbit metal The tin base and lead base babbits are widely used as a

bearing material, because they satisfy mostrequirements for general applications.

The babbit is generally used as a thin layer, 0.05 mm to0.15 mm thick, bonded to an insert or steel shell. Thecomposition of the babbit metals is as follows:

Tin base babbits : Tin 90% ; Copper 4.5% ; Antimony5% ; Lead 0.5%.

Lead base babbits : Lead 84% ; Tin 6% ; Anitmony9.5% ; Copper 0.5%.

IES 2011Babbit is an alloy of

(a) Sn, Cu, Sb and Pb

(b) Sn and Cu

(c) Sn, Cu and Pb

(d) Sn, Cu and Sb

IES-1995Babbit lining is used on brass/bronze bearings to

(a) Increase bearing resistance

(b) Increase compressive strength

(c) Provide anti-friction properties

(d) Increase wear resistance.

IES-2009Why are babbit alloys used for bearing material?

(a) They have excellent embeddability

(b) They are relatively stronger than other bearing materials

(c) They do not lose strength with increase in temperature

(d) They have high fatigue strength

IES-2008Which one of the following is correct?

Babbitt are used for

(a) Gears (b) Bearings

(c) Bolts (d) Clutch liners

IESTin base white metals are used where the bearings are subjected to

(a) Large surface wear

(b) Elevated temperatures.

(c) Light load and pressure

(d) High pressure and load.

IES-1998Match List-I (Alloys) with List-II (Applications) and select the correct answer using the codes given below the lists:

List-I List-II

A. Chromel 1. Journal bearing

B. Babbit alloy 2. Milling cutter

C. Nimonic alloy 3. Thermocouple wire

D. High speed steel 4. Gas turbine blades

Code:A B C D A B C D

(a) 3 1 4 2 (b) 3 4 1 2

(c) 2 4 1 3 (d) 2 1 4 3

IES-2005Match List I (Alloy) with List II (Major Constituent) and select the correct answer using the code given below the Lists:

List I List II

A. Babbitt 1. Nickel

B. Invar 2. Tin and lead

C. Gun Metal 3. Aluminium

D. Duralumin 4. Copper

Code:A B C D A B C D

(a) 2 4 1 3 (b) 3 1 4 2

(c) 2 1 4 3 (d) 3 4 1 2

IES 2007Match List I with List II and select the correct answer using the code given below the Lists:

List I List II(Component) (Required Property)A. Blades of bulldozer 1. High wear resistance and

high toughnessB. Gas turbine blades 2. Low Young’s modulus and

high fatigue strengthC. Drill bit 3. High wear and abrasion

resistanceD. Springs of automobiles 4. High creep strength and

good corrosion resistanceCode: A B C D A B C D

(a) 3 2 1 4 (b) 1 4 3 2(b) 3 4 1 2 (d) 1 2 3 4

Columbium/Niobium Columbium finds much use in large-scale applications,

such as steel for automobile bodies and pipelines. The usethat probably will consume most of the columbium ismicroalloying.

Relatively small amount of columbium lend high strengthto steel. The microalloyed, or high-strenght, low-alloy(HSLA) steels, are used for automobile bodies, structuresof all kinds, and high-pressure pipe, particulary in the oiland gas industry.

Columbium with oxygen as dominant substiutitionalalloying atoms is used in the nuclear fusion reactor.

Nuclear material refers to the metals uranium, plutonium,and thorium, in any form, according to the IAEA

IES 2011Columbium is a :

(a) Nuclear material

(b) Automobile material

(c) Film material

(d) Foam material

Nimonic 90 A precipitation hardenable nickel-chromium-cobalt alloy,

having high stress-rupture strength and creep resistance atelevated temperatures up to about 950 °C.

For springs exposed to lower loads, the material can be usedup to 700 °C.

Nimonic 90 offers good resistance to corrosion and is non-magnetic.

Applications include the aircraft industry, gas turbines,vehicle components and springs in high temperatureenvironments, and thermal.

Operating temperature: -100 – + 550 °C

The End