Question

Which of the following is an alloy of aluminium? (a) magnallium (b) duralumin (c) brass (d) both (a) and (b)

Short answer

The correct answer is (d) both (a) and (b).

Step-by-step solution

Understanding Alloys

An alloy is a mixture of metals, often created to take advantage of specific properties such as strength or resistance to corrosion. Here we need to identify which options are alloys of aluminium.

Identify the Components of Each Alloy

- **Magnallium** is an alloy consisting mainly of aluminium and magnesium. - **Duralumin** is composed primarily of aluminium, along with copper, manganese, and magnesium. - **Brass** is an alloy made from copper and zinc, containing no aluminium.

Evaluate the Options

Since both magnallium and duralumin contain aluminium as one of their main components, these are the correct alloys of aluminium. Brass does not contain aluminium, so it is not relevant to the question.

Determine the Correct Answer

Both options (a) magnallium and (b) duralumin are alloys of aluminium as they both include aluminium as a primary constituent. Therefore, the correct answer must be the option that includes both.

Key concepts

Properties of Alloys

Alloys are fascinating materials as they combine two or more metals to create a new substance with unique properties. This process is known as alloying. By blending different metals together, scientists are able to enhance certain physical or chemical characteristics that wouldn't be achieved by individual metals on their own.
Aluminium alloys, such as magnallium and duralumin, showcase some remarkable properties:

• Lightweight: Aluminium alloys are known for being less dense than other metals, making them ideal for applications where weight is a concern, such as in the aerospace industry.
• Strength: By combining metals, such as magnesium or copper, the strength of aluminium is significantly increased.
• Corrosion resistance: Aluminium naturally forms a protective oxide layer, and this characteristic is retained and often enhanced when alloyed.
• Malleability and ductility: These alloys can be shaped and formed easily without breaking.

Each property can be optimized by altering the composition of the alloy, allowing engineers and designers to tailor materials to suit specific applications.

Composition of Metals

The composition of an alloy is a crucial factor that determines its characteristics and uses. When creating an alloy, the primary metal, known as the base metal, is combined with secondary metal elements to enhance or add properties.

• Base Metal: This is the principal metal in the alloy, dictating many of its core properties. Aluminium, for instance, is the base metal in magnallium and duralumin.
• Secondary Metals: These are additional metals that are mixed with the base metal. Each of these elements contributes distinct properties:
  • Magnesium: Increases strength and adds corrosion resistance.
  • Copper: Enhances strength and hardness, commonly used in draughting, electrical and military applications.
  • Manganese: Improves wear resistance, also enhancing strength.

By carefully adjusting these combinations, alloy designers can create a substance that achieves the desired balance of characteristics for diverse industrial needs.

Use of Alloys in Industry

Alloys serve as the backbone of countless industries because of their specialized properties. Their ability to provide solutions that pure metals cannot is unmatched. Let's explore some industrial applications of aluminium alloys:

• Aerospace: Lightweight aluminium alloys, such as duralumin, are essential for aircraft structures because they reduce weight while maintaining strength, which is crucial for fuel efficiency and load capacity.
• Automotive: Magnallium is used in transportation for similar reasons, offering cars that are lighter and more fuel-efficient without compromising safety.
• Marine: The anti-corrosive properties of aluminium alloys make them perfect for shipbuilding and harbour infrastructure.
• Construction: Aluminium alloys are also prominent in building applications including windows, doors, and roofing materials, providing strength and aesthetic appeal while resisting corrosion.

The versatility of alloys not only fuels innovation but also enhances sustainability by enabling the development of greener technologies.