Melting Point of Aluminum: Tudo o que precisa de saber

Aluminum is a lightweight metal with different alloys. It is commonly used in various industries due to its excellent properties. One of the properties that is important in manufacturing aluminum is its melting point.

Read the guide below to learn about what’s the melting point of aluminum and whether different aluminum alloys have different melting points.

What’s the Melting Point of Aluminum?

The melting point of aluminum is the temperature at which its solid state turns to liquid. Aluminum melting point is relatively low compared to many other metals like steel or titanium.

The melting point plays an important role in the production, recycling, and applications of aluminum. Aluminum is easy to melt and shape into different forms like car parts, airplane components, or cans.

How Pure Aluminum is Produced?

Here are the steps on how to transform raw bauxite into pure aluminum ready for manufacturing:

1. Extracting Bauxite Ore

Bauxite is a sedimentary rock that can be mined from tropical and subtropical regions. It contains aluminum.

2. Refining Bauxite

Using the Bayer process, caustic soda solution will chemically extract aluminum oxide from bauxite to produce alumina.

3. Smelting Alumina

Alumina is a white, odorless powder that needs to undergo electrolysis to produce liquid aluminum. Collect the pure aluminum that settles at the bottom of the smelter.

4. Casting

Pour the collected molten aluminum into molds to create ingots, billets, or other forms for industrial use.

What are The Melting Points of Different Forms of Aluminum?

Alumínio has different forms, which makes it versatile. Each form has its own melting point that needs to be known so you can choose the right alloy for your application.

Pure Aluminum Metal

Pure aluminum has a melting point of 660.3°C (1220.54°F). This low melting point means that it is soft and easy to shape.

Copper-Aluminum Alloys

Copper-aluminum alloys have a melting point range of 500-650°C (932-1202°F). These alloys are stronger and more wear-resistant. They are preferred to be used in aerospace and automotive applications.

Magnesium-Aluminum Alloys

Magnesium-aluminum alloys have a melting point range of 450-630°C (842-1166°F). These alloys are lighter than copper-aluminum alloys, so they are ideal for lightweight components needed for aerospace and automotive use.

Aluminum Oxides

Aluminum Oxide has a melting point of 2072°C (3762°F). This high melting point makes it ideal for applications requiring extreme heat resistance, like ceramics, refractories, and abrasives.

Melting Point of Aluminum Alloys

Below is a table where you can compare the melting points of different aluminum alloys:

What Factors Can Affect the Melting Point of Aluminum?

There are factors that are important when selecting the appropriate aluminum alloy for your specific application, especially in industries that require precise thermal properties. Here are some of the factors:

Alloy Composition

The addition of other elements, such as silicon, cobre, and magnesium, can significantly affect the melting point of aluminum.

A specific combination of these elements determines the overall melting behavior of an aluminum alloy.

Alloys with higher concentrations of elements like copper or magnesium tend to have a lower melting point compared to pure aluminum.

Purity of Aluminum

The presence of impurities, like other metals or oxides, can either raise or lower the melting point of an aluminum alloy.

Generally, aluminum with higher purity will have a more consistent and predictable melting point.

Temperatura e pressão

While aluminum typically melts at the same temperature under normal atmospheric pressure, increasing or decreasing pressure can affect its melting point slightly.

Higher pressure can raise the melting point, while lower pressure may reduce it.

External temperatures, like environmental heat or cooling, can also affect the melting point of aluminum during certain manufacturing processes.

For example, aluminum may have slight variations in melting behavior at different processing temperatures.

How Can Impurities in Aluminum Affect Its Melting Point?

Impurities can either make the melting point of aluminum higher or lower– depending on their nature and concentration.

Here are some elements that can affect aluminum’s melting point:

Ferro (Fe)

Ferro can increase aluminum’s melting point. Even small amounts of iron create hard, brittle phases such as iron-aluminum intermetallics that affect the melting behavior– often leading to a higher melting point than pure aluminum.

It can also negatively impact the strength and ductility of the aluminum alloy.

Silício (Si)

Silicon lowers the melting point of aluminum. This is beneficial in aluminum casting because it makes the aluminum alloy easier to melt and pour.

It also improves fluidity but may reduce the strength of the material. For example, in aluminum-silicon alloy, silicon reduces the melting point which makes it ideal for casting.

Copper (Cu)

Copper lowers aluminum’s melting point. Higher copper content can lead to a broader solidification range. The solidification range is the difference between the liquidus and solidus temperatures.

It may be harder to precisely control the melting and solidification processes because of the broader range. It also increases the strength and hardness, but excessive copper can result in poor corrosion resistance.

Magnesium (Mg)

Magnesium has a similar effect to copper as it slightly lowers the melting point of aluminum. However, magnesium increases the alloy’s strength and hardness, especially at elevated temperatures.

Alloys like 5052 and 6051 contain magnesium and have good weldability and corrosion resistance. Magnesium typically does not significantly change the melting point but can broaden the solidification range.

Zinc (Zn)

Zinco typically lowers the melting point of aluminum, though the effect is lesser than for silicon. Zinc is used in alloys like the 7xxx series to enhance strength, particularly in aerospace applications.

Zinc’s impact on the melting point is more about the alloy’s solidification range and the resulting physical properties rather than a dramatic decrease in the melting point.

How to Reduce Impurities on Aluminum’s Melting Point

To reduce impurities that can affect aluminum’s melting point, you can rely on refining, alloying, and filtration processes.

These steps help ensure aluminum is of high quality, with more predictable melting behavior and improved mechanical properties.

Refining

Refining aluminum involves removing impurities from the raw material to increase its purity. This can be achieved through techniques such as the Bayer Process, which is used to extract alumina (aluminum oxide) from bauxite, or through electrolytic refining.

The more refined the aluminum, the closer its melting point will be to that of pure aluminum (660.3°C or 1220.54°F).

Refining reduces the presence of undesirable impurities, ensuring a more consistent melting behavior.

Liga

Carefully adding other elements, such as copper, silicon, or magnesium, to aluminum to form alloys can help control the melting point.

Proper alloying can offset the effects of impurities and result in an alloy with better performance characteristics.

For example, adding magnesium to aluminum can improve its strength and corrosion resistance, which may reduce the need for high purity in certain applications.

Alloying allows for controlled changes in melting points and can improve the physical properties of aluminum for specific uses, especially in industries like aerospace and automotive.

Filtration

Filtration involves removing solid impurities and particles from molten aluminum. This can be done by passing the molten metal through filters that catch impurities before the aluminum is solidified into ingots or cast into molds.

Filtration systems help clean the aluminum and prevent the inclusion of impurities that could affect the melting point.

By filtering out unwanted particles, the quality of the aluminum is improved, leading to better consistency in the melting point and overall material properties.

Difference Between Pure Aluminum, Scrap, and Hardeners

Pure aluminum is nearly 100% aluminum, with low strength but high corrosion resistance and conductivity. You can use it for packaging and electrical conductors.

Scrap aluminum comes from recycled products and may include pure aluminum or alloys with impurities. Its quality varies, and it often requires refining before you can reuse it to create new products.

Hardeners are alloying elements like copper, magnesium, silicon, and zinc added to aluminum to improve strength and durability. You can use these alloys for high-performance applications.

Applications of Aluminum Based on Melting Point

The melting point of aluminum and its alloys significantly influences their applications. Here are some of the common applications:

Pure Aluminum

Due to its excellent electrical conductivity, pure aluminum is commonly used in power cables and electrical transmission lines. Since it’s corrosion-resistant, it is also used in aluminum foil and food packaging.

Lightweight and corrosion-resistant, pure aluminum is used in some non-structural parts of aircraft and vehicles.

Aluminum Alloys with Lower Melting Points

Alloys like 2024 e 7075 are used for aircraft components due to their high strength and lower melting point compared to pure aluminum. These alloys are also commonly used in automotive frames and engine parts, especially in high-performance vehicles.

Alloys such as 5052 are resistant to corrosion, making them ideal for marine applications.

Aluminum Alloys with Higher Melting Points

Due to their high strength and heat resistance, alloys like 7075 are used in military aircraft, spacecraft, and structural components where extreme strength and resistance to high temperatures are crucial.

These alloys are also used for high-performance machinery and tooling.

Aluminum Oxide (Alumina)

Due to its extremely high melting point, aluminum oxide is used in high-temperature applications such as furnace linings and kiln furniture.

Aluminum oxide is also used in sandpapers and grinding wheels due to its hardness and durability.

Conclusão

The melting point of aluminum is important for its use and production.

DEK is an expert in knowing which aluminum works well in different industries. Contact us now, and we will make sure to use the right material for your specific application.