INDEX
SI no: Title Page no:
1. Introduction 2
Some common alloys
2. 3
3. Uses of an alloy 6
Analysis of an alloy
4. 7
5. Experiment 1 8
6. Experiment 2 10
7. Conclusion 13
8. Bibliography 15
1
Introduction
An alloy is a mixture or metallic solid solution composed of two
or more elements. Complete solid solution alloys give single
solid phase microstructure, while partial solutions give two or more
phases that may or may not be homogeneous in distribution, depending
on thermal (heat treatment) history. Alloys usually have different
properties from those of the component elements.
The term alloy is used to describe a mixture of atoms in which the
primary constituent is a metal. The primary metal is called the base,
the matrix, or the solvent. The secondary constituents are often
called solutes. If there is a mixture of only two types of atoms, not
counting impurities, such as a copper-nickel alloy, then it is called
a binary alloy. If there are three types of atoms forming the mixture,
such as iron, nickel and chromium, then it is called a ternary alloy. An
alloy with four constituents is a quaternary alloy, while a five-part
alloy is termed a quinary alloy. Because the percentage of each
constituent can be varied,
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SOME COMMON ALLOYS :
Amalgam
Any alloy of mercury is called an amalgam. Most metals are soluble in
mercury, but some (such as iron)are not. Amalgams are commonly
used in dental fillings because they have been relatively cheap, easy to
use, and durable. In addition, until recently, they have been
regarded as safe. They are made by mixing mercury with silver ,copper
,tin , and other metals. The mercury content of dental fillings
has recently stirred controversy, based on the potentially harmful
effects of mercury. Mercury amalgams have also been used in the
process of mining gold and silver, because of the ease with
which mercury amalgamates with them. In addition ,
thallium amalgam is used as the liquid material in thermometers,
because it freezes at 58°C,whereas pure mercury freezes at -38°C.
Brass
A decorative brass paperweight (left), along with zinc and copper
samples. Brass is the term used for alloys of copper and zinc in a solid
solution. It has a yellow color, somewhat similar to gold. It was
produced in prehistoric times, long before zinc was discovered, by
melting copper with calamine, a zinc ore. The amount of zinc in brass
varies from 5 to 45 percent, creating a range of brasses, each with
unique properties. By comparison, bronze is principally an alloy of
copper and tin. Despite this distinction, some types of brasses are
called bronzes. Brass is relatively resistant to tarnishing and is
often used for decorative purposes. Its malleability and acoustic
properties have made it the metal of choice for musical
instruments such as the trombone, tuba, trumpet, and euphonium.
Although saxophones And harmonicas are made out of brass, the
saxophone is a woodwind instrument, and the harmonica, a free reed
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aero phone. In organ pipes designed as "reed" pipes, brass strips are
used as the "reed." Aluminum makes brass stronger and more
corrosion-resistant. It forms a transparent, self-healing, protective
layer of aluminum oxide (Al2O3) on the surface. Tin has a
similar effect and finds its use especially in seawater applications
(naval brasses). Combinations of iron, aluminum, silicon, and
manganese make brass resistant to wear and tear.
Bronze
Bronze refers to a broad range of copper alloys, usually with tin as the
main additive, but sometimes with other element s such as
phosphorus,manganese,aluminum, or silicon. Typically, bronze is
about 60 percent copper and 40 percent tin. The use of bronze
was particularly significant for early civilizations, leading to the name
"Bronze Age." Tools, weapons, armor, and building materials
such as decorative tiles were made of bronze, as they were found to be
harder and more durable than their stone and copper predecessors.
In early use, the natural impurity arsenic sometimes created a superior
natural alloy, called "arsenical bronze." Though not as strong as steel,
bronze is superior to iron in nearly every application. Bronze develops
a patina (a green coating on the exposed surface), but it does not
oxidize beyond the surface. It is considerably less brittle than iron and
has a lower casting temperature. Several bronze alloys resist
corrosion (especially by seawater) and metal fatigue better than steel;
they also conduct Heat and electricity better than most steels. Bronze
has myriad uses in industry. It is widely used today for springs,
bearings, bushings, and similar fittings, and is particularly common in
the bearings of small electric motors. It is also widely used for cast
metal sculpture and is the most popular metal for top-quality bells and
cymbals. Commercial bronze, otherwise known as brass, is 90 percent
copper and 10 percent zinc. It contains no tinwith any mixture the
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entire range of possible variations is called a system. In this respect, all
of the various forms of an alloy containing only two constituents, like
iron and carbon, is called a binary system, while all of the alloy
combinations possible with a ternary alloy, such as alloys of iron,
carbon and chromium, is called a ternary system. The complete
analysis of an alloy involves two steps, qualitative and quantitative
analysis. In qualitative analysis, the components of the alloy are found
out and in quantitative analysis their percentage composition is
determined. The purpose of this project is to determine qualitatively,
the contents of samples of Brass and Bronze.
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Uses of Alloys
i) To modify chemical reactivity:-
a. When sodium is used as reducing agent it is too reactive to be used
but its alloy with mercury, called sodium amalgam can be safely
used as reducing agent.
ii) To increase hardness:-
b. Hardness of gold is increased by adding copper to it. Also zinc is
added to copper to make copper hard in form of brass.
iii) To increase tensile strength:-
c. Nickeloy, an alloy of Nickel (1%), Copper (4%) and aluminium
(95%) has high tensile strength.
iv) To lower the melting point:-
d. Solder metal which is an alloy of Sn(30%) and Pb(70%) has very
less melting point as compared to melting points of Sn and Pb.
v) To modify the colour:-
e. Aluminium bronze an alloy of Cu and Al has a beautiful golden
colour.
vi) To resist corrosion:-
f. Iron gets rusted and corroded. Its corrosion takes place with time but
for stainless steel, an alloy of iron (98%) and carbon (2%) does not
get rusted.
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Analysis of an alloy
The complete analysis of an alloy involves two steps.
1. Qualitative Analysis :
This involves identification of the components of the alloys.
2. Quantitative Analysis :
This involves determination of the components of the alloy. It
involves the separation of the components from the alloy
quantitatively followed by determination of percentage of each
component volumetrically or gravimetrically. In this project we will
carry out qualitative analysis only.
Objectives of Project :
In this project, our aim is to know the various metals present in the
given sample of alloy.
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Experiment 1
To analyze a sample of brass qualitatively.
Aim:
To analyze a sample of brass qualitatively.
Requirements:
China dish, test-tube funnel, filter paper and common laboratory reagents.
Theory:
Brass is an alloy of copper and zinc with the following
Composition:
Cu = 60-90% and Zn. = 10-40%.
Thus Cu and Zn. form the main constituents of brass. Both these metals dissolved
in 50% of nitric acid due to formation of nitrates which are soluble.
3Cu + 8HNO3 → 3Cu(NO3)2 + N2O + 5H2O
4Zn + 10HNO3 → 4Zn (NO3)2 + N2O + 5H2O
The solution is boiled to expel the oxides of nitrogen and the resulting solution is
tested for Cu2+ and Zn2+ ions.
Procedure:
1. Place a small piece of brass in a china dish and heat this with minimum quantity
of 50% HNO3 so as to dissolve the piece completely.
2. Continue heating the solution till a dry solid residue is obtained.
3. Dissolve the solid residue in dil. HCl and filter. Add distilled water to the
filtrate.
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4. Pass H2S gas through the filtrate. A black precipitate of copper sulphide is
obtained. Separate the black ppt. and keep the filtrate for the test of Zn 2+ ions
Dissolve black ppt. by heating them with 50% HNO3. To this solution add
ammonium hydroxide solution. Appearance of deep blue colouration in the
solution shows the presence of copper ions in the solution.
5. To test Zn2+ ions, boil the filtrate to remove H2S gas, then add solid NH4Cl to
this and heat to dissolve NH4Cl. Add excess of NH4OH so that a solution is
ammoniacal. Now pass H2S gas through this ammoniacal solution. Dirty white or
grey precipitation indicate zinc.
6. Separate the precipitates and dissolve it in minimum amount of dil. HCl. Boil
to expel H2S gas and add potassium Ferro cyanide solution, white or bluish white
ppt. confirm Zn2+ ions in the solution.
Result:
The given sample of brass contains copper and zinc metals as the main
constituents.
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Experiment 2
To analyze a sample of bronze qualitatively.
Aim:
To analyze a sample of bronze qualitatively.
Requirements:
China dish, test-tube funnel, filter paper and common laboratory reagents.
Theory:
Bronze is an alloy of copper and tin with the following.
Composition:
Cu = 88-96% and Sn. = 4-12%.
Thus copper and zinc form the main constituents of bronze. Both these metals
dissolved in nitric acid.
Cu + HNO3 → Cu2+ + NO + H2O
Sn + HNO3 →H2SnO3 + NO2 + H2O
(Conc. acid) (Metastannic Acid)
Excess of nitric acid is removed by heating the solution. The resulting solution
now would contain Cu2+ ions and metastannic acid. This solution is acidified with
dil. HCl and H2S gas is passed when the sulphides of copper and tin are formed.
Cu2+ + S2 → CuS (Black ppt.)
H2SnO3 + 2H2S→ SnS2 (Black ppt.) + 3H2O
The sulphides are separated by boiling the ppt. with yellow ammonium sulphide
when SnS2 goes into solution as thiostannate where as CuS is not affected.
SnS2 + (NH4)2S →(NH4)2 SnS2 (Soluble)
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Ammonium thiostannate.
CuS + (NH4)2S→ CuS (Unaffected)
Black ppt.
The soluble black ppt. is tested for Cu2+ ions and the solution is tested for
Sn2+ ions as in elementary qualitative analysis.
Procedure:
1. Take about 1g. of small pieces of bronze in a china dish and add to it 5-10 ml.
of dil. HNO3.
2. Heat the contents slowly to dissolve copper and tin completely and then boil
the contents to a paste to remove excess of HNO3. All this is carried out in cup
board.
3. Dissolve this dry mass in distilled water containing HCl (1:1) to get a clear
solution.
4. Transfer the solution in a test tube and pass H2S in excess i.e. till the
precipitation is complete. Filter and reject the filtrate.
5. Take the black ppt. in a test tube and add to it 2-3 ml. of yellow ammonium
sulphide and heat. Filter the contents. Black residue is tested for Cu 2+ ions and
filtrate is tested for Sn2+ ions.
6. Analysis of black residue:
Transfer a little of the black ppt. into a test tube. Add to it 2-3 ml. of 50%. HNO3
and boil the contents of the tube. A light blue or green sol. indicates the presence
of Cu2+. Divide this sol. into two parts.
(a) To one part add excess of NH4OH a deep blue colouration confirms the
presence of Cu2+ ions.
(b) Acidify the second part with acetic acid and add K4 [Fe (CN)6] i.e. potassium
ferrocyanide solution. A reddish brown ppt. confirms the presence of Cu 2+ ions.
7. Analysis of filtrate:
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Boil the filtrate with 1 ml. of dil. HCl. A yellow ppt. is obtained. Dissolve in 1
ml. conc. HCl. To this solution add 0.5 g. of zinc dust and boil it for 2-3 minutes.
Filter and to filtrate add 1-2 ml. of mercuric chloride solution. A white ppt.
turning grey on standing confirms the presence of Sn4+ ions.
Result:
The given sample of bronze contains - Copper and Tin as the main constituents.
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Conclusion
In this project, a qualitative analysis of two samples of alloys namely, Brass and
Bronze, was carried out to determine their constituents. The given sample of
bronze contains - Copper and Tin as the main constituents and the given sample
of bronze contains - Copper and Tin as the main constituents.
Studying the constituents of alloys is crucial for understanding their properties,
applications, and behavior in various industries. Alloys are combinations of two
or more elements, with at least one being a metal, and are designed to enhance
certain characteristics such as strength, corrosion resistance, and heat
conductivity, among others. The study of these constituents—both metal and non-
metal—enables scientists and engineers to tailor materials to meet specific needs,
whether it be in construction, aerospace, electronics, or even healthcare.
Understanding the composition of alloys helps to predict how they will perform
under different conditions. For example, adding carbon to iron creates steel,
which can be further modified with elements like chromium, nickel, or
molybdenum to produce stainless steel, each variant offering different qualities
such as resistance to corrosion, enhanced strength, or improved ductility. By
studying the proportions of these elements, scientists can optimize alloys for
particular tasks, ensuring they provide maximum performance and durability in
their intended applications.
One significant aspect of studying alloy constituents is the exploration of phase
diagrams. These diagrams provide a graphical representation of the different
phases of an alloy at various temperatures and compositions, helping to predict
the alloy's behavior during processes like casting, forging, or heat treatment. This
knowledge is invaluable for controlling the microstructure of an alloy, which
directly affects its mechanical properties, such as hardness, tensile strength, and
brittleness.
Moreover, the study of alloy constituents is not just limited to metals. Non-
metallic elements, like carbon in steel or silicon in aluminum alloys, can also
significantly influence an alloy's behavior. These non-metals can form
compounds or alter the bonding structure of the alloy, changing its physical and
chemical properties. Thus, a deep understanding of all constituents, whether
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metallic or non-metallic, allows for the precise engineering of materials with the
desired performance characteristics.
In conclusion, the study of alloy constituents is a fundamental aspect of materials
science and engineering. It provides essential insights into the relationship
between composition, structure, and properties, enabling the design of advanced
materials suited for diverse and demanding applications. With ongoing
advancements in technology, such as additive manufacturing and
nanotechnology, a more detailed understanding of alloy composition will
continue to play a pivotal role in creating next-generation materials that meet the
evolving needs of modern industries.
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Bibliography
1.scribd
2.chatgpt
3.wikipedia
4.academia.edu
5.hsu projects
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