Metals are one of the most common elements we see in our daily life. Aluminum foil, gold and silver ornaments are made up from metals only.
There are different types of metal placed separately in periodic table.
1. Alkali metals
These metals are placed in 1st group of periodic table. They are highly reactive and soft metals. They form basic oxide in their aqueous solution, therefore known as alkali metal. Most common examples of alkali metals are sodium, potassium, lithium etc.
2. Alkaline Earth Metals
These metals are located in 2nd group of periodic table like calcium, magnesium etc. They are found in earth crust so called as alkaline earth metals.
3. Transition Metals
These metals are located from 3rd to 12th group of periodic table. They are most common metals used in daily life like iron, cooper, zinc, gold, silver etc. These metals are very hard, malleable and ductile in nature, therefore can be convert in sheets or wires for various uses. They are good conductor of heat and electricity, therefore also used in electrical circuits and equipment.
These metals are placed separately at the bottom of periodic table. Due to less abundance in nature, they are also known as rare elements. Compare to transition metals, they are silvery soft metals with high melting point. These metals and their compounds are mainly used in lasers, lamps, magnets and to improve the properties of other metals.
These metals are placed below lanthanides in periodic table. They are reactive and radioactive metals, mainly used in medicines and nuclear devices.
Similarly German silver is an alloy of copper, zinc and nickel and non-magnetic in nature. When copper and gold are mixed together, it forms pink alloy which looks quite different from its constituent metals.
- Uses of metals are not new for human beings as many human civilizations are related to metals. For a long time, we are using metals to meet our needs.
- But metals do not have unlimited characteristics, they also have some limits. Like some metals; aluminum, zinc are not so strong metals.
- Iron gets rusted due to atmospheric oxidation and cooper metal also gets a green color layer of carbonate and oxide over it.
- All most all pure metals have weak strength and easily bends. This is due to weak metallic bonds between same size atoms which become weaker under stress due to sliding of atoms over each other.
- To overcome these all limitations, a new concept of alloys introduced. Alloy is a mixture of metals in certain composition. They show different physical and chemical properties compare to metals.
- For example; bronze is an alloy of tin and copper. It is composed of 12% tin and 88% of copper. Bronze is harder than its constituent metals and easier to use for various applications.
- Since alloys melt at a range of temperature instead of a sharp melting point like metals, they can be used for different purposes.
- The appearance of alloy depends upon their composition. Like white gold is an alloy of nickel and gold, looks like nickel.
For the improvement of properties of metals, alloys produced. Alloys are prepared by mixing of metals on their molten state. The molten mixture of metals is poured in sand moulds to get solidify. Alloys must contain those metals which are miscible into each other in their molten state, otherwise after casting; metals would separate into two layers.Alloys can be a combination of metals and non-metals.
Each constituent element of alloy is known to have its own specific set of properties. Various combinations of metals can create different alloys which show different chemical and physical properties. The constituent metals of alloy cannot be separated by physical processes.Some common examples of alloys are as follow.
Alloys are not a new material for us as we have been used them since pre-historic times. Man used alloys soon after he worked with metals and have created many alloys which are suitable for particular objects. Some alloys like White Gold (gold with nickel or palladium) has limited uses while other alloys such as bronze, steel, and brass have changed our history and our modern world.
It is an alloy of copper and tin. It was first alloy to be made by alloying copper with arsenic and used by human civilization. Since arsenic shows toxic effects, therefore later it replaced by tin. Bronze is mainly used to make utensils like jugs, pans, pots, vases as well as to make weapons and armor. It also uses to make tools like hammers, mallets, wrenches and instruments such as bells, saxophones and cymbals.
It is a combination of metals and non-metals. As we know, iron metals get rust in atmospheric air, hence to create resistance to corrosion in iron; it gets mix with some other metals like chromium, manganese, molybdenum and non-metals like carbon. The percentage of carbon changes the hardness of metal. While addition of chromium provides shine to metal surface and molybdenum makes steel stronger.
The trace of tungsten makes steel more durable. In general steel is composed of 95% iron, up to 2% carbon, and trace quantities of other metals. This composition may vary in different types of steel.Composition of various grades of steel is as follow.
| Chemical Composition of Steel
|| C % Max
|| Mn % Max.
|| P%Max .
In the manufacturing of steel, first refine the pig iron in blast furnace to remove all impurities except little carbon. Than other trace metals are added to refine metal. Steel is mainly used to make cutlery,armor, utensils, weapons and tools.
It is a bright, shiny alloy composed of copper and zinc. It is more malleable compare to its constituent metals and has low melting point. Therefore it can be easily melt and mold in various shapes. It mainly used to make musical instruments like the trombone, the tuba, the trumpet and the French horn.
Due to shiny gold like appearance, it may also use to make decorative objects. Since it is more malleable and ductile compare to copper and zinc, it is widely used into pipes and electrical wires.
Alloys show quite different properties compare to their constituent metals. They show quite batter properties than metals. For example; steel is an alloy of iron and used as building material due to high strength. Similarly brass and bronze can easily mold in various shapes compare to constituent metals.
Bronze which is an alloy of copper and tin has more resistance to corrosion and widely used is ship-building. Titanium alloys are less dense and stronger compare to other metals. Therefore they mainly used in ship, aircraft, and spacecraft. Generally pure metals are less useful sue to more softness. For example; Gold is very soft in pure state and cannot use to manufacture ornaments. Therefore gold is mixed with other metals like silver, copper, or zinc.
These additional metals impart various properties and change appearance of gold. The properties of alloys are influenced by the manner of formation and treatment of alloy. The post-heat treatment and physical process can also modify the properties of alloys. Alloys are chemically more stable than their constituent metals; therefore alloys are designed for specific resistance to actions like corrosion, fatigue, wear, and temperature.
Some other properties of alloys are as follow -
- Steel is an alloy of iron, chromium and nickel with carbon. Each of elements imparts some unique characteristic to steel like resistance to corrosion and shiny surface.
- Alloy of beryllium and copper are stronger and good conductor of electricity.
- Alloy of gallium and arsenic used as superconductor in laser-beam technology.
- Due to their corrosion- and heat-resistance, alloys of nickel and cobalt are used in aircraft engines.
- Alloys of aluminum with silicon, iron, copper, manganese, magnesium and zinc are specifically designed for the manufacture of beverage cans.
- An alloy of tin with minor amounts of antimony and copper is known as pewter.
- Alloys of copper with zinc brass used for a variety of fittings, and copper with tin; bronze is used for plumbing fixtures.
- The combination of more than one metal or other element is formed metallic material called an alloy.
- Alloys are formed by mixing of metals through different physical processes like fusion, electrolytic deposition, etc.
- Generally metals like zinc, copper, tin, chromium, nickel, silver are used to prepare alloys with other metals and non-metals like carbon, boron, sulfur, zinc, etc.
- The composition of metals in alloy determines the chemical and physical properties of alloys.
- On the basis number of metals present in alloys, they can be classified as binary, ternary alloys and so on.
- Binary alloys created by the combination of two metals while ternary alloys are formed by three elements.
Some other common types of alloys are as follow -
1. Aluminium Alloys
Due to good conductivity, aluminium metal is useful for a variety of applications. The main disadvantage of this metal is less strength which can be overcome by addition of other metals to form alloys. For example, alnico is composed of aluminium, magnalium is composed of nickel, iron and cobalt with base metal aluminium and alloy with copper is called as duralumin.
2. Copper Alloys
Like iron, copper is also prone to oxidation and turns surface dull and pale-greenish. Therefore the formation of alloys of copper prevents the oxidation and increases its strength. For example; brass contains 80% copper with 20% zinc. Another alloy of copper is bronze contains 10% tin.
3. Iron Alloys
Steel is the most common alloy of iron which is composed of 95% iron with some content of carbon and other metals. The presence of carbon contents prevents iron metal from rusting and increase its strength. Other example of iron alloys are Invar, Fermico and Kovar.
4. Gold Alloys
Due to high malleability of pure gold, it cannot use to make jewellery. For example; alloy of gold with copper, silver and cobalt is known as yellow gold. Similarly white god is composed of gold, copper, zinc, nickel and trace amount of palladium.
There are many possible combinations of different metals to form alloys. Each alloy has its own specific properties and uses. The uses of alloys depend upon the composition of metal and complexity of alloy. Some common uses of alloys are as follow.
- Uses of aluminum alloys: Compare to aluminum, alloys of aluminum are good conductor and more strong. Due to these properties, they are widely used in the manufacturing of automotive engine part, electrical equipment and in furniture. Due to high strength they are also used in high altitude flying to bear huge pressure and stress.
- Uses of copper alloys: Like copper metal, alloys are copper are good conductor of heat and electricity, have high ductility and corrosion resistance. They are mainly used in automotive heat exchanger, sleeve bearing and in the manufacturing of electrical equipments.
- Uses of Nickel alloys: Alloys of nickel have good corrosion resistance and heat resistance. Therefore they are used for aircraft gas turbines, petrochemical industries, control equipment and nuclear power systems.
- Uses of Iron alloys: Stainless steel is one of the most common alloys of iron which is used for many commercial purposes. Iron alloys are mainly used in agriculture electronic and rail industries.
- Uses of Titanium alloys: Alloys of titanium have high strength, stiffness and toughness, therefore mainly used in aerospace and high-performance applications like for spacecraft parts. Jet engines and airframes. They have wide applications in bio-material and petrochemical industries also.