Development of Light Alloys

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Development of Light AlloysDevelopment of Light AlloysABHIJIT GHOSH

ROLL NO.--00070301018

U.G. -4thYEAR

METALLURGICAL AND MATERIAL ENGG.

PROJECT TEACHER: PROF. A.K. PRAMANIK



SCOPESCOPE

y Light alloys have become of great importance in

engineering for construction of transportation

equipment. Many of these light weight alloys

have sufficiently high strength to warrant theiruse for structural purposes ,and as a result of

their use ,the total weight of transportation

equipment has been considerably decreased.

Probably the greatest application of light metalsis in the construction of aircraft.



y At present ,the metals that serves as the

base of the principal light alloys are

aluminum and magnesium .Titanium and

its alloys are included in this group sincethey have density much lower than that of

steel.



AluminiumAluminium alloyalloy

y Aluminium alloys are alloys in which aluminiumis the predominant metal. Typical alloyingelements are copper, zinc, manganese, silicon, andmagnesium. There are two principal classifications,

namely casting alloys and wrought alloys, both of which are further subdivided into the categoriesheat-treatable and non-heat-treatable. About 85%of aluminium is used for wrought products, for

example rolled plate, foils and extrusions. Castaluminium alloys yield cost effective products dueto the low melting point, although they generallyhave lower tensile strengths than wrought alloys.



y Aluminium alloys are widely used inengineering structures and componentswhere light weight or corrosion resistance isrequired.

y Aluminium alloy surfaces will keep theirapparent shine in a dry environment due tothe formation of a clear, protective oxidelayer. In a wet environment, Galvanic

corrosion can occur when an aluminiumalloy is placed in electrical contact withother metals with a more negative corrosionpotential than aluminium.



AluminiumAluminium alloys versus steelsalloys versus steels

y Aluminium alloys typically have an elasticmodulus of around 70 GPa, which is aboutone third the elastic modulus of steel. For a

given load, a part made of an aluminium alloywill therefore show greater elasticdeformation than a steel part of identicalgeometry. Though there are aluminium alloys

with higher tensile strengths than commonlyused steels, simply replacing steel parts withaluminium alloy equivalents may lead toproblems.



y In automotive engineering, cars made of

aluminium alloys employ space frames made

of extruded profiles to ensure rigidity. This

represents a radical change from thecommon approach for current steel car

design, which depend on the body shells for

stiffness, that is a unibody design.

y An important structural limitation of

aluminium alloys is their lower fatigue

strength compared to steel.



AluminiumAluminium ² ² Copper AlloysCopper Alloys

y Copper has been the most common

alloying element almost since the

beginning of the aluminum industry, and a

variety of alloys in which copper is themajor addition were developed. The alloy

composition, used in this experiment, is

(95.5weight percent Al, 4.5 weight percentCu)



Partial phase diagram of aluminumPartial phase diagram of aluminum² ²coppercopper

The range of dural umin type of alloys is shaded.

In the cast alloys the basic structure consists of cored dendrites of aluminum

solid solution, with a variety of constituents at the grain boundaries or

interdendritic spaces, forming a brittle, more or less continuous network of

eutectics.



(annealed)

Microstructure

Aluminum(95.5%)-

Copper (4.5%) alloy

the microstructure contains two solid phases. The matrix

is (-Al) phase with inter-metalic ppt.(CuAl)



AluminumAluminum--Zinc alloyZinc alloy

y Metals that have the same crystal structure (likesilver and gold) are usually completely miscible(they don·t separate into two or more phasesupon cooling). When alloys are made from metals

with different crystal structures, a tendencyusually exists for different phases to form in thealloy upon cooling. The aluminum (AI)/zinc (Zn)alloy studied in this experiment is an example of amaterial that undergoes a phase transformationupon cooling or heating . Aluminum has a face-centered cubic crystal structure, and zinc has ahexagonal-closest packed crystal structure .



Phase Diagram for Aluminum and ZincPhase Diagram for Aluminum and Zinc

y The alloy composition used in this experiment (89weight percent Al, 11 weight percent Zn) . So,theannaeled microstructure contains two solid phases.In this experiment, one phase () will be mostly Aland the other phase() will be mostly Zn.

Weight Percent Zinc

Temp(°C)



(annealed)

Microstructure

Aluminum(89%)-

Zinc(11%) alloy

the microstructure contains two solid phases. The matrix

is () phase and the other phase is () phase



FARTHER TASKSFARTHER TASKS

y Study the mechanical &corrosion

properties of the developed samples.

y Also, study ageing characteristiks.

y Developing alloys of different

composition.



THANK YOUTHANK YOU

Development of Light Alloys

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