What Are the Physical Properties of Aluminum?

Aluminum is one of the most widely used metals in the world. Found in everything from aircraft and skyscrapers to smartphones and food packaging, aluminum owes its popularity to its unique combination of physical properties. These characteristics make it ideal for applications that demand strength, lightweight, corrosion resistance, and versatility.

In this detailed SEO article brought to you by sasaalloy, we’ll explore the physical properties of aluminum, explain how they impact its performance, and why aluminum remains a top material choice across modern industries.

1. Introduction to Aluminum

Aluminum (chemical symbol: Al) is the third most abundant element in Earth’s crust and the most abundant metal. It is a silvery-white, lightweight, and non-magnetic metal that is used extensively in transportation, construction, electrical systems, packaging, and more.

Aluminum belongs to the group of post-transition metals and is typically used in pure form or as part of aluminum alloys such as 6061, 5052, and 7075. While its chemical behavior is essential, it’s the physical properties of aluminum that make it so valuable in real-world applications.

2. Key Physical Properties of Aluminum

1. Low Density

One of the most defining physical properties of aluminum is its low density.

• Density of pure aluminum: 2.70 g/cm³

• This is about one-third the density of steel or copper

This low weight makes aluminum perfect for applications where weight reduction is critical, such as aerospace, automotive, and portable electronics.

2. High Strength-to-Weight Ratio

Although aluminum is lightweight, it still offers excellent strength, especially when alloyed with elements like magnesium or silicon.

• Pure aluminum: relatively soft

• Aluminum alloys: high tensile strength, ranging from 100 MPa to over 600 MPa

This makes aluminum both light and strong—ideal for load-bearing applications in bridges, buildings, and aircraft.

3. Excellent Thermal Conductivity

Aluminum is an excellent conductor of heat:

• Thermal conductivity: ~235 W/m·K

• This is about three times higher than steel

Due to this property, aluminum is widely used in heat sinks, radiators, air conditioners, and cookware.

4. Good Electrical Conductivity

Aluminum is also a good conductor of electricity:

• Electrical conductivity: ~37.7 million S/m (about 60% that of copper)

• Despite lower conductivity than copper, its lower density makes it more efficient per unit weight

That’s why aluminum is extensively used in power lines, transformer windings, and electrical bus bars.

5. Corrosion Resistance

Aluminum naturally forms a thin oxide layer on its surface when exposed to air. This layer protects it from further corrosion.

• Naturally self-passivating

• Resistant to most weather and environmental conditions

• Especially valuable in marine, outdoor, and chemical settings

Many aluminum alloys supplied by sasaalloy are designed to enhance this corrosion resistance for harsh environments.

3. Mechanical Properties

1. Hardness

Pure aluminum is relatively soft but becomes much harder when alloyed or cold-worked.

• Brinell hardness: 15 HB (pure aluminum)

• Up to 150 HB for certain high-strength alloys like 7075

2. Elastic Modulus

The modulus of elasticity for aluminum is:

• ~69 GPa (10 million psi)

• Lower than steel (~200 GPa), which means aluminum is more flexible under load

3. Melting Point

• Melting point of aluminum: 660.3°C (1220.5°F)

• Lower than most structural metals

This allows aluminum to be easily cast, extruded, or machined.

4. Surface Properties

1. Reflectivity

Aluminum has high reflectivity in both visible and infrared light:

• Reflects ~92% of visible light

• Reflects ~98% of infrared radiation

This makes aluminum an excellent choice for lighting fixtures, solar panels, thermal insulation, and mirror finishes.

2. Color and Luster

• Naturally silver-white and shiny

• Can be anodized, painted, or polished for enhanced appearance and corrosion protection

At sasaalloy, we offer both mill finish and surface-treated aluminum for decorative and functional purposes.

5. Workability and Formability

Aluminum is easy to work with, making it a favorite for manufacturers.

• Ductility: Can be drawn into wires

• Malleability: Can be rolled or pressed into thin sheets

• Formability: Excellent for bending, stamping, and deep drawing

Its workability varies by alloy and temper. For example:

• 5052 and 1100 are known for high formability

• 6061 and 7075 offer strength but require more controlled forming methods

6. Magnetic and Acoustic Properties

1. Non-Magnetic

Aluminum is non-magnetic, making it ideal for:

• MRI machines

• Magnetic shielding

• Electrical enclosures

2. Non-Sparking

Aluminum does not spark when struck, making it safe for use in:

• Explosive environments

• Petrochemical plants

• Fire-safe equipment

7. Physical Performance in Extreme Conditions

1. Cryogenic Temperatures

Unlike many metals, aluminum retains or even improves its toughness at very low temperatures, making it excellent for:

• Cryogenic storage tanks

• Spacecraft and satellite structures

• Liquid natural gas (LNG) transport

2. Elevated Temperatures

Aluminum loses strength more rapidly than steel at temperatures over 150°C. Special alloys or reinforcement may be required for high-temperature applications.

8. Recyclability and Sustainability

One of aluminum’s most overlooked but valuable physical properties is its recyclability.

• 100% recyclable without loss of properties

• Recycling uses only ~5% of the energy required to produce primary aluminum

• Helps reduce environmental impact and production costs

sasaalloy offers eco-friendly aluminum solutions using high-quality recycled material when required.

9. Comparison with Other Metals

This table highlights why aluminum is often selected over other materials when a balance of performance, weight, and cost is needed.

10. Conclusion: What Are the Physical Properties of Aluminum?

Aluminum is a lightweight, strong, corrosion-resistant, and highly versatile metal. Its physical properties—including low density, excellent thermal and electrical conductivity, high reflectivity, and non-magnetic nature—make it a superior choice for countless applications across aerospace, construction, transportation, marine, electronics, and consumer products.

At sasaalloy, we specialize in supplying high-performance aluminum materials in sheets, plates, bars, coils, tubes, and custom profiles. We serve industries around the world with reliable quality, technical expertise, and fast delivery.