Aluminium Alloy – Properties, Composition, Applications

In this article we are going to learn about Aluminium Alloy, different types of aluminium alloys and it’s properties.

What is meant by Aluminium Alloy ?

An aluminium alloy is a material made primarily of aluminium with the addition of other elements. When aluminium is molten (liquid), the elements are mixed together and cooled to form a homogeneous solid solution. The other elements may account for up to 15% of the alloy’s bulk.

Iron, copper, magnesium, silicon, and zinc are among the other elements. In comparison to the pure metallic element, the addition of elements to aluminium improves the alloy’s strength, workability, corrosion resistance, electrical conductivity, and/or density. Aluminum alloys are lightweight and resistant to corrosion.

Aluminium finds its widest uses when alloyed with small amounts of other metals. The addition of small quantities of other alloying elements converts this soft, weak metal into a hard and strong metal, while still retaining its light weight. Alloys can be classified as cast or wrought, both groups containing alloys that are age-hardened. The alloys in each of these two classes are further classified according to whether they respond to heat treatment of the strengthening type.

For the casting of general engineering use, aluminium is alloyed with small amounts of copper and zinc in the proportion of 12.5 to 14.5 per cent zinc and 2.5 to 3.0 per cent copper. An important series of casting and forging alloys having high strength have recently been developed for use in airplane construction. One example of such alloys is : zinc 5 per cent, magnesium 3 per cent, copper 2.2 per cent, nickel up to 1 aluminium the remainder. per cent.

Types of Aluminium Alloy

The aluminium may be easily alloyed with other elements like copper, magnesium, zinc,manganese, silicon and nickel to improve various properties. The addition of small quantities of alloying elements into other metals helps to converts the soft and weak metal into hard and strong metal, while still retaining its light weight. Various aluminium alloys are

1. Duralumin,
2. Y-alloy,
3. Magnalium and
4. Hindalium

These Aluminium alloys are discussed below :-

1. Duralumin

It is an important wrought alloy. Its composition contains following chemical contents.
Copper = 3.5-4.5%
Manganese = 0.4-0.7%
Magnesium = 0.4-0.7%
Aluminium = 94%

Properties

Duralumin can be very easily forged, casted and worked because it possesses low melting point. It has high tensile strength, comparable with mild steel combined with the characteristics lightness of Al. It however possesses low corrosion resistance and high electrical conductivity.

This alloy possesses higher strength after heat treatment and age hardening. After working, if this alloy is age hardened for 3 or 4 days. This phenomenon is known as age hardening.

It hardens spontaneously when exposed to room temperature. This alloy is soft enough for a workable period after it has been quenched. It is light in weight as compared to its strength in comparison to other metals. It can be easily hot worked at a temperature of 500°C. However after forging and annealing, it can also be cold worked.

Applications

Duralumin is used in the wrought conditions for forging, stamping, bars, sheets, tubes, bolts, and rivets. Due to its higher strength and lighter weight, this alloy is widely used in automobile and aircraft components.

To improve the strength of duralumin sheet, a thin film of Al is rolled along with this sheet. Such combined sheets are widely used in air-craft industries. It is also employed in surgical and orthopedic work, non-magnetic work and measuring instrument parts constructing work.

2. Y alloy

Y-Alloy is also called copper-aluminium alloy. The addition of copper to pure aluminium increases its strength and machinability. Its composition contains following chemical contents.

Copper = 3.5-4.5%
Manganese = 1.2-1.7%
Nickel = 1.8-2.3%
Silicon, magnesium, iron = 0.6% each
Aluminium = 92.5%.

Properties

The addition of copper in aluminium increases its strength and machinability. Y-alloy can be easily cast and hot worked. Like duralumin, this alloy is heat treated and age hardened. The age-hardening process of Y-alloy is carried out at room temperature for about five days.

Applications

Y-Alloy is mainly used for cast purposes, but it can also be used for forged components like duralumin. Since Y -alloy has better strength than duralumin at high temperatures, therefore it is much used in aircraft engines for cylinder heads, pistons, cylinder heads, crank cases of internal combustion engines die casting, pump rods etc.

3. Magnalium

Magnalium is an alloy of aluminium, magnesium, copper, nickel and tin etc. It contains
Al = 85 to 95%, Cu = 0 to 25%, Mg = 1 to 5%,
Ni = 0 to 1.2%, Sn = 0 to 3%, Fe = 0 to 0.9%,
Mn = 0 to 0.03%, Si = 0.2 to 0.6%.

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

Properties

Magnalium is light in weight and brittle. This alloy possesses poor castability and good machinability. It can be easily welded.

Applications

Due to its light weight and good mechanical properties, it is mainly used for making aircraft and automobile components.

4. Hindalium

Hindalium is a common trade name of aluminium alloy. It is an alloy of aluminium, magnesium, manganese, chromium and silicon etc. In India, it is produced by Hindustan Aluminium Corporation Ltd., Renukoot (U.P.). Hindalium is commonly produced as a rolled product in 16 gauges. Utensils manufactured by this alloys are strong and hard, easily cleaned, low cost than stainless steels, having fine finish, having good scratch resistance, do not absorb much heat etc.

Applications of aluminium alloy

Aluminium alloys have numerous applications across various industries due to their excellent properties such as lightweight, corrosion resistance, high strength-to-weight ratio, and good formability. Some common applications of aluminium alloys include:

1. Aerospace Industry: It is widely used in aircraft structures, including fuselage panels, wings, and structural components, due to their lightweight nature and high strength.
2. Automotive Industry: It is used to manufacture engine blocks, wheels, body panels, and other components to reduce the overall weight of vehicles, enhancing fuel efficiency and performance.
3. Construction: It is utilized in construction for windows, doors, roofing, and curtain walls due to their corrosion resistance and ability to withstand various weather conditions.
4. Packaging: It is commonly used in the production of beverage cans and food packaging due to their ability to protect the contents and maintain hygiene.
5. Electrical Industry: It is employed in electrical conductors and cables due to their high electrical conductivity.
6. Marine Applications: It is used for shipbuilding and marine structures due to their corrosion resistance and lightweight properties.
7. Sports Equipment: It is utilized in the production of sports equipment such as bicycles, baseball bats, and tennis rackets, as they offer strength while remaining lightweight.
8. Industrial Equipment: It is employed in manufacturing industrial equipment like heat exchangers, pressure vessels, and pipes due to their corrosion resistance and thermal conductivity.
9. Consumer Goods: It is used in various consumer products, including household appliances, furniture, and electronics.
10. Medical Devices: It find applications in medical devices such as wheelchairs, prosthetics, and medical equipment due to their lightweight and biocompatibility.

These are just a few examples of the wide-ranging applications of aluminium alloys. Their versatility and favorable properties make them an essential material in modern industries.

advantages of aluminium alloy

Aluminium alloys offer a range of advantages that make them popular and widely used in various applications. Some of the key advantages of aluminium alloys include:

1. Lightweight: It has a low density, making them significantly lighter than other commonly used metals like steel. This property is particularly beneficial in industries such as aerospace and automotive, where reducing weight is crucial for fuel efficiency and performance.
2. High Strength-to-Weight Ratio: Despite being lightweight, aluminium alloys possess excellent strength-to-weight ratios. They can withstand significant loads and stresses, making them suitable for structural applications in aerospace, automotive, and construction industries.
3. Corrosion Resistance: Aluminium naturally forms a thin, protective oxide layer on its surface, which provides inherent corrosion resistance. This characteristic allows aluminium alloys to withstand exposure to harsh environments, making them ideal for marine, architectural, and industrial applications.
4. Formability: It is highly malleable and can be easily formed into various shapes and sizes through processes such as rolling, extrusion, and casting. This property enables their use in intricate designs and complex structures.
5. Electrical Conductivity: It possess excellent electrical conductivity, making them valuable in electrical transmission lines, conductors, and other electrical components.
6. Thermal Conductivity: It exhibit good thermal conductivity, making them suitable for heat exchangers, radiators, and other heat transfer applications.
7. Non-Magnetic: It is non-magnetic, which is beneficial in certain industries where magnetic interference must be avoided, such as in electronic devices and MRI equipment.
8. Recyclability: Aluminium is highly recyclable, and the recycling process requires significantly less energy compared to the production of primary aluminium. This property contributes to sustainability and reduces environmental impact.
9. Aesthetic Appeal: It can be easily finished with various surface treatments, such as anodizing or powder coating, offering a wide range of colors and finishes for aesthetic purposes.
10. Cost-Effective: It is generally more cost-effective compared to other high-performance materials like titanium or carbon fiber, making them a practical choice for many applications.

Due to these advantages, aluminium alloys find extensive use in diverse industries, from aerospace and automotive to construction, electronics, and consumer goods. Their combination of properties makes them a versatile and valuable material choice for various engineering applications.

disadvantages of aluminium alloy

While aluminium alloys offer numerous advantages, they also have some disadvantages that should be considered when choosing them for specific applications. Some of the key disadvantages of aluminium alloys include:

1. Lower Strength compared to Some Metals: While aluminium alloys have a high strength-to-weight ratio, they may still have lower strength compared to certain other metals, such as steel and titanium. In applications where extremely high strength is required, other materials may be more suitable.
2. Susceptible to Galvanic Corrosion: When in contact with certain dissimilar metals, aluminium alloys can undergo galvanic corrosion, leading to accelerated corrosion rates. Proper insulation or coating is necessary to prevent this type of corrosion in specific environments.
3. Lower Melting Point: It has a lower melting point compared to some other metals, which can be a limitation in high-temperature applications or processes.
4. Formability Limitations: Although aluminium alloys are generally highly formable, some high-strength alloys may have limitations in terms of forming complex shapes or undergoing multiple forming processes without a risk of cracking.
5. Cost: While aluminium is relatively cost-effective, some high-performance, It may still be more expensive than traditional materials like steel.
6. Limited Weldability: It can be challenging to weld, especially without proper techniques and equipment. Welding of aluminium may require skilled personnel and specialized processes.
7. Lower Wear Resistance: In certain applications where abrasive wear is a concern, it may have lower wear resistance compared to other materials like hardened steel.
8. Non-Magnetic: While non-magnetism can be an advantage in some cases, it can also be a disadvantage in applications that require magnetic properties.
9. Creep Deformation: At elevated temperatures and under sustained loads, some aluminium alloys can experience creep deformation, which may limit their use in high-temperature applications.
10. Electrical Conductivity in Certain Applications: While aluminium’s electrical conductivity can be advantageous in some cases, it can be a disadvantage when electrical insulation is required.

Despite these disadvantages, aluminium alloys remain widely used and preferred in numerous applications due to their unique combination of properties and overall benefits. Proper engineering and material selection can help mitigate some of the limitations associated with aluminium alloys in specific use cases.

Check Out Other Important Topics

Different Types of Steel & Constituents of Steel

Steel Making Process – Complete Overview with Flowchart

Cast Iron – Properties, Types & Uses

Recovery Recrystallization and Grain Growth – Working Process

Constrained Motion – Definition, Types, Examples, Images