Metallurgy & Materials ScienceDr.S.JoseDept of Mechanical Engg.,TKM College of Engineering, Kollamdrsjose@gmail.com

*Module IVFerrous MaterialsNon ferrous alloysComposite MaterialsMetal matrix composites Smart Materials.Nano materialsBio materialsBioplastics.

Copper and alloysAluminium and alloysMagnesium and alloysTitanium and alloys

Non ferrous alloys

*Most extensively used among non ferrous materialsImportant properties are excellent electrical conductivity and corrosion resistanceIt occupies the second place among engineering materials. It is also having very good thermal conductivity, and also it can be easily machined, welded, brazed and soldered. But, it lacks sufficient strength which makes it unsuitable for structural applications

Copper

*Over 50% of the copper produced is used for electrical purposes like wires, switches and other articles which carry electric currentAnother chunk of copper goes into applications which require higher thermal conductivityThese applications include, automotive radiators, water heaters, refrigerators, heat exchangers, condensers etcDue to the excellent corrosion resistance, copper and its alloys find widespread usage in corrosive environments

Copper

*Strength of copper can be increased by different methods like strain hardening, solid solution strengthening and precipitation hardening.Among these, most effective method is the second one which is achieved by alloying of copper by addition of elements like zinc, tin, aluminium etc. to form solid solutions. The solid solution alloys of copper are brasses, bronzes, cupronickels and nickel-silvers.

Copper

*Brass is an alloy of copper and zinc with the zinc content varying from 5 to 54%. Small amounts of lead, tin or aluminium also are added to impart specific properties to brassThe important properties of brass are Good strength, ductility and formability Good machinability Good electrical and thermal conductivity Good wear and corrosion resistances Non-magnetic Good aesthetic property

Brass

Copper-Zinc Phase diagram

*A wide variety of brasses are in use today.Solubility of zinc in a-solid solution increases from 32.5% at 900C to about 38% at 455C. Copper and the a-solid solution are having FCC structures, while the -solid solution is of BCC structure. In the -phase, copper and zinc atoms are randomly dispersed at lattice points. Based on the type of solid solution formed, the commercial brasses are broadly classified into two categories a-brasses and duplex brasses.

Brass

*Yellow -brass: Cartridge brass: Admiralty brass: Aluminium brass: Red -Brass: Gilding metal: Leaded red brass:

-Brasses

*Muntz metal: Naval brass: Forging brass:

Duplex or ( + ) Brasses

*The term, bronze represents alloys of copper with elements other than zinc. The simplest bronze contains 88% Cu with 12% tin. Other alloying elements like phosphorous, lead, nickel etc. are also added to obtain favorable properties. Other than tin, elements like aluminium, silicon or beryllium are also alloyed with copper producing different bronzes. Zinc also may be present in these alloys in relatively smaller amounts. Bronzes are softer and weaker than steel. Corrosion resistance, heat and electric conductivity are also better than steel, while the cost is higher than steels. Compared to brasses, these are having lower coefficient of friction, higher strength, toughness, corrosion resistance and also higher cost. Bronze is having good castability and anti-friction or bearing properties. Bronzes are widely used for different purposes like bearings, springs, industrial castings, bells and statues.variety of brasses are in use today.Solubility of zinc in a-solid solution increases from 32.5% at 900C to about 38% at 455C. Copper and the a-solid solution are having FCC structures, while the -solid solution is of BCC structure. In the -phase, copper and zinc atoms are randomly dispersed at lattice points. Based on the type of solid solution formed, the commercial brasses are broadly classified into two categories a-brasses and duplex brasses.

Bronzes

*Bronzes are softer and weaker than steel. Corrosion resistance, heat and electric conductivity are also better than steel, while the cost is higher than steels. Compared to brasses, these are having lower coefficient of friction, higher strength, toughness, corrosion resistance and also higher cost. Bronze is having good castability and anti-friction or bearing properties. Bronzes are widely used for different purposes like bearings, springs, industrial castings, bells and statues.

Bronzes

*Tin Bronze: Gun metal: Aluminium bronze: Silicon bronze: Beryllium bronze:

Bronzes

*Aluminium occupies the third place among commercially used engineering materials. It has low density, low melting point and high electrical and thermal conductivities. It has low strength and hardness, but high ductility and malleability. Aluminium

*On exposure to atmosphere, it forms a strong film of aluminium oxide on its surface, which prevents further oxidation and corrosion. It is employed for lightly loaded structures and for electrical cables and similar items.Aluminium has good machinability, formability, workability and castability. It is non-magnetic, non-toxic, easily available and less expensive.The main drawback is its low strength and hardness.Aluminium

*The poor tensile strength of aluminium can be increased by many methods like strain hardening, solid solution hardening, age hardening and fiber reinforcement. By cold working, tensile strength of aluminium can be increased by two times due to strain hardening. Addition of alloying elements like copper, manganese, magnesium, silicon etc. can increase the strength of aluminium upto four times by forming solid solutions. Aluminium alloys

Aluminium- Copper phase diagram

*Maximum solubility of copper in aluminium is 5.65% at 550OC and it reduces to 0.45% at 300OC. Alloys containing between 2.5 and 5% copper will respond to heat treatment by age hardening. Due to the increased strength, aluminium alloys are widely used in commercial applications. Two main groups of aluminium alloys are wrought alloys and casting alloys. Aluminium alloys

*Wrought alloys : Al-Mn and Al-Mg alloys form homogenous solid solutions and are characterized by comparatively lower strength and high ductility. Other examples are avial (Al-Mg-Si) and duralumin (Al-Cu-Mg).Casting alloys: The best known casting alloy is the silumin alloys. Alloys of Al and Cu also are suitable for casting. Many of the casting alloys are heat treatable.

Aluminium alloys

*Duralumin: A typical composition is 94% Al, 4% Cu and 0.5% each of Mg, Mn, Si and Fe. High tensile strength and electrical conductivity. Widely used for aeroplanes, surgical and orthopedic equipments.Y-alloy: Composition of this alloy is 92.5% Al, 4% Cu, 2% Ni and 1.5% Mg. High strength and hardness even at high temperature such as 200oC. Used for cylinder heads and crank cases of engines.

Aluminium alloys

*Magnelium: The major alloying elements in this alloy are magnesium and copper with Ni, Sn, Fe, Mn and Si in small amounts. Better tensile strength and machinability, but it is brittle. Used by aircraft and automobile industries. Silumin alloys: Alloys based on Al-Si system are known as silumin alloys. A typical silumin is the eutectic alloy with 88% Al and 12% Si. Having good castability, corrosion resistance, high ductility and low density.

Aluminium alloys

*Titanium has two allotropic forms: upto 880OC, it exists as a-titanium (HCP)and at higher temperatures as -titanium (BCC)It is a strong, ductile and light weight metal, density of pure Ti is 60% of steel. High corrosion resistance and high strength at elevated temperatures and widely used as a structural material. Suitable for cold and hot working and has good weldability. Machinability is much inferior to steel.Titanium

*The most important alloying elements for titanium are Al, Cr, Mn, V, Fe, Mo and Sn which considerably increase the mechanical strength. Higher creep resistance, higher fatigue strength, highest specific strength and good corrosion resistance. Responds to heat treatment by precipitation hardening.Ti-6Al-4V is the most widely used alloy, accounting for about 45% of total titanium production.

Titanium Alloys

*Used for aerospace structures and turbines due to the high specific strength, corrosion resistance and strength at elevated temperature. Titanium is used in the construction of leaching and purification plants for cobalt production. Due to the higher corrosion resistance, titanium is also used in various chemical processing equipments, valves and tanks.

Uses of Titanium Alloys

*Magnesium has the HCP crystal structure. It is lighter and less ductile than aluminium.It is having poor modulus of elasticity, poor resistance to wear, fatigue and creep. Its response to strengthening mechanisms also is relatively poor. Solubility of aluminium in magnesium increases with temperature This alloy responds well to age hardening alsoMagnesium

*Addition of aluminium to magnesium increases strength, hardness and castability.Addition of manganese to magnesium has very little effect on the mechanical properties, but it improves the corrosion resistance. Magnesium-aluminium-zinc alloys have higher mechanical properties and good corrosion resistance. In general, magnesium alloys have poor ductility and formability, but poor fatigue and stress corrosion resistance.

Magnesium Alloys

*Magnesium alloys are used in the areas of aerospace, high speed machinery, transportation and material handling equipments. Magnesium-manganese alloys are used for sheet forming processes. Magnesium-aluminium-zinc alloys are suitable for sand and die casting, extrusion and forging processes.

Magnesium Alloys

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