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Aluminum alloy is popular for its low weight and high strength features. Besides, they have corrosive resistance too. All these make aluminum alloy suitable for versatile applications, including automotive, aerospace, consumer goods, and more.
In this guide we’ll explore aluminum alloy in depth: its composition, features, properties, types, and more. So, Let’s begin:
What Is Aluminum Alloy?
In aluminum alloy, other elements like silicon, zinc, copper, etc are added to aluminum at a specific proportion. This alloy formation enhances the mechanical and physical properties of aluminum.
Compared to pure aluminum, aluminum alloy is more durable and has better physical and chemical properties. This makes them suitable for various applications. For example, alloy of aluminum and magnesium is very lightweight and works best for aerospace uses.
What Is Aluminum Alloy Made Of?
In aluminum alloy, pure aluminum is melted to its liquid stage, and alloying elements are added to it. These elements can make up to 15% of the alloy by mass. The most common alloying elements added with aluminum are as follows:
Major Alloying Element:
- Copper (Cu)
- Manganese (Mn)
- Magnesium (Mg)
- Silicon (Si)
- Zinc (Zn)
Minor Alloying Element:
- Chromium (Cr)
- Titanium (Ti)
- Iron (Fe)
- Nickel (Ni)
- Lithium (Li)
Basic Features Of Aluminum Alloy
- Corrosion resistance
- Lightweight
- High ratio of strength to weight
- Low melting point
- Electrical conductive
- Thermal conductive
- Formable
- No magnetic interference
- Recyclable
Properties Of Aluminum Alloy
a. Physical Properties
The physical and mechanical properties of aluminum alloy varies for different ranges. Such versatility makes it suitable for varying applications.
| Aluminum Alloy Series | Melting Point (°C) | Tensile Strength (MPa) | Yield Strength (MPa) | Density (g/cm³) | Electrical Conductivity (% IACS) | Thermal Conductivity (W/m·K) |
|---|---|---|---|---|---|---|
| 1000 Series | 660 | 70 – 180 | 30 – 110 | 2.71 | 60 – 65 | 230 – 235 |
| 2000 Series | 510 – 635 | 400 – 520 | 275 – 345 | 2.78 | 30 – 40 | 140 – 190 |
| 3000 Series | 600 – 655 | 110 – 285 | 95 – 185 | 2.73 | 40 – 50 | 160 – 180 |
| 4000 Series | 577 – 630 | 200 – 380 | 180 – 300 | 2.70 | 30 – 40 | 140 – 170 |
| 5000 Series | 580 – 640 | 200 – 350 | 90 – 290 | 2.68 | 28 – 32 | 160 – 210 |
| 6000 Series | 580 – 650 | 240 – 310 | 120 – 270 | 2.70 | 40 – 50 | 160 – 210 |
| 7000 Series | 475 – 635 | 450 – 600 | 380 – 500 | 2.80 | 30 – 35 | 130 – 150 |
| 9000 Series | Varies by composition | Varies by composition | Varies by composition | 2.74 | Varies by composition | Varies by composition |
b. Chemical Properties
Aluminum alloy is highly resistant to corrosion. However, the chemical properties varies for different compositions. These are as follows:
| Alloy Series | Alloying Elements | Oxidation Resistance | Reactivity | Corrosion Resistance | Coating Requirement |
|---|---|---|---|---|---|
| 1000 Series | 99%+ Al | High | Low | Excellent | No |
| 2000 Series | Al, Cu | Moderate | High | Moderate | Yes |
| 3000 Series | Al, Mn | High | Moderate | Good | No |
| 4000 Series | Al, Si | Moderate | Moderate | Good | No |
| 5000 Series | Al, Mg | High | Low | Excellent | No |
| 6000 Series | Al, Mg, Si | High | Moderate | Good | No |
| 7000 Series | Al, Zn | Moderate | High | Moderate | Yes |
| 9000 Series | Varies by composition | Varies by composition | Varies by composition | Varies by composition | Varies by composition |
Types of Aluminum Alloys
1. Cast Alloys
Cast aluminum alloys are composed of major alloying elements like- silicon, copper, magnesium, or zinc. You can create complex shapes by melting cast aluminum alloy and pouring it into molds. They are widely used in household items, mechanical parts, and the automobile industry.
2. Wrought Alloys
Wrought aluminum alloys are mechanically processed through extrusion, rolling, or forging. This gives the aluminum alloy greater strength and durability. Based on strengthening via heat treatment, wrought alloys can be of two types:
- Heat-treatable aluminum alloys
- Non-heat-treatable aluminum alloys
3. Series Classification
Based on the alloying materials and properties, aluminum alloy is classified in to the following series:
| Series Of Aluminum Alloy | Primary Alloying Element | Properties | Applications |
|---|---|---|---|
| 1000 Series | Pure Aluminum (≥99% Al) | 1. Excellent corrosion resistance 2. High electrical and thermal conductivity 3. Good workability 4. Low strength | Electrical conductors, chemical equipment, food packaging, heat exchangers |
| 2000 Series | Copper | 1. High strength and hardness 2. Lower corrosion resistance 3. Not weldable | Aerospace structures, truck frames, aircraft components |
| 3000 Series | Manganese | 1. Excellent formability 2. Good corrosion resistance 3. Workability 4. Moderate strength | Food and beverage packaging, kitchen equipment, chemical tanks |
| 4000 Series | Silicon | 1. High fluidity 2. Low melting point 3. Good wear resistance 4. High thermal conductivity | Automotive engine parts, brazing filler metals, heat exchangers |
| 5000 Series | Magnesium | 1. High corrosion resistance 2. Moderate to high strength 3. Good weldability 4. Not heat-treatable | Marine structures, pressure vessels, fuel tanks, vehicle bodies |
| 6000 Series | Magnesium & Silicon | 1. Good corrosion resistance 2. Moderate strength 3. Good machinability 4. Excellent weldability 5. Heat-treatable | Structural applications, automotive parts, construction materials, bridge and rail components |
| 7000 Series | Zinc (and sometimes Copper) | 1. Very high strength 2. Lower corrosion resistance 3. Heat-treatable | Aerospace frames, high-stress components, sporting goods, automotive suspension parts |
Benefits Of Using Aluminum Alloy
Lightweight Yet High Strength
Aluminum alloy is lightweight and has high strength. These features make them highly suitable for applications sensitive to weight. For example, in automotive, aluminum alloy is used to make the vehicles lightweight, saving fuel usage. Again, the lightweight feature of the aluminum alloy makes it ideal to use in aerospace.
Corrosion Resistance Makes Them Suitable For Rough Environment
The formation of a thin oxide layer on the aluminum surface makes it highly resistant to corrosion. So, you can use aluminum alloy outdoors, in marine environments, in the chemical industry, and in applications that deal with moisture contact.
The durable and long-lasting nature of aluminum alloy removes the hassle of frequent replacement. Thus, using aluminum alloy reduces maintenance hassles and saves money.
Versatile Application
Aluminum alloys are highly flexible, making them suitable for versatile applications. You can create complex structures by forging, rolling, casting, or extruding aluminum alloys. For example- aluminum alloy is used in the casing of laptops, smartphones, and other electrical devices.
Thermal and Electrical Conductivity
Aluminum alloys have high electrical and thermal conductivity features. This makes them suitable for applications that require electrical transmission or heat dispersion. For example- aluminum alloy is used in wiring systems, heat sinks, and conductors.
Recyclable and Sustainable
You can separate aluminum from the alloying element with only a fraction of the energy. This makes them highly recycled, reducing their carbon footprint. Companies that are aware of sustainability prioritize the use of recycled aluminum, promoting a green environment.
Cost Efficiency
Though the initial cost of aluminum alloy is high, in the long run, it’s cost-effective. As aluminum alloy is durable, you need not frequently replace them. This will save you money. Again, its lightweight features also save you transportation costs.
Limitations Of Aluminum Alloy
- Low melting point: Compared to metal like steel, aluminum alloy has a low melting point. This makes them unsuitable for applications that deal with high temperatures.
- Susceptibility to deformation: Under high stress and heavy load, aluminum alloys can get deformed. However, with proper engineering and design, this risk can be minimized.
- Less strength compared to some other metals: Though aluminum alloys offer higher strength compared to weight, they are not as strong as steel or titanium. Therefore, where higher strength is required, aluminum alloy may not be a suitable choice.
- Challenges in welding: As aluminum alloy has higher thermal conductivity, it can be challenging to weld.
Application Of Aluminum Alloy
Aerospace & Automotive
Aluminum is about one-third of steel’s weight. This lightweight feature makes them suitable materials for building automotive and aerospace parts. By reducing the vehicle weight, aluminum alloy maximizes efficiency and fuel sustainability in the long run. Besides, this alloy also performs well on crash tests.
Electrical and Electronic Sector
Aluminum alloy is non-magnetic, which is essential for electronic manufacturing, electrical shielding, etc. Besides, they are good conductors of electricity. That is why aluminum alloy is widely used in electronic devices.
Building and Construction
Aluminum alloy is the second primary element (steel stands first) used for building structures. As it is lightweight and has high strength, it is a popular metal for builders and construction industries.
Medical Equipment
Aluminum alloys are widely used in surgical instruments and other medical devices. As they are durable and rust-free, using aluminum alloy is an excellent choice for medical applications. Besides the hospital beds, wheelchairs, etc., are also made of aluminum alloy. Moreover, they are also used in medical implants. (e.g., bone plates and screws) due to their biocompatibility.
Consumer Good
Cookware, utilsense, beverage cans, and casing of laptops/smartphones are made of aluminum alloy. As it is lightweight and anti-corrosive, you can carefreely use products of aluminum alloy for day-to-day use.
What is the Process Of Making Aluminum Alloy?
Step 1: Collecting Raw Material
The key raw material for aluminum alloy is bauxite ore. It is mined from the earth and sent for processing.
Step 2: Refining Alumina
Next the extracted bauxite is crushed and a mixture is made by adding sodium hydroxide to it. Once this solution is heated, you will get pure alumina precipeted at the bottom of the container. Filter it and proceed to the next step.
Step 3: Electrolysis
Now, you need to run an electrolysis to get pure aluminum metal. All you need to do is add molten cryolite to alumina and let it dissolve. The electrolysis conducted here follows the Hall-Héroult process.
Step 4: Adding Alloying Element To Pure Aluminum
This is the main step where alloying elements like zinc, silicone, etc are added to form aluminum alloy. However, you must follow the correct proportion in adding these elements to aluminum.
Step 5: Casting
Once you get the desired alloy, it’s time to shape them up. Here, the aluminum alloy is melted and poured into different molds. After molding the aluminum alloy to a definite shape, you can use different heat treatments to strengthen its mechanism.
Step 5: Forming
To get the final product, you need to implement various methods like forging, rolling extrusion, or CNC machining.
How To Strengthen Aluminum Alloy?
Method 1: Solid Solution Strengthening (Alloying)
In the solid solution strengthening process, when the alloying elements are added to aluminum and solidified, it enhances aluminum strength. Common alloying elements used in the Thai process include- copper, magnesium, manganese, and silicon.
Method 2: Strain Hardening (Cold Working)
In this method, the aluminum alloy is deformed at low temperatures. The dislocation in the aluminum alloy enhances its strength. For example, at room temperature, the yield strength of pure aluminum is 4 KSI (30 MPa). In contrast, the yield strength reaches 24 KSI (165 MPa) in a fully cold-worked state.
Method 3: Precipitation (age) Hardening
In the precipitation hardening process, tiny particles are formed inside the aluminum alloy. These particles are very small, with a diameter of less than 0.001 mm. However, you can not strengthen all types of aluminum alloy with this process; only 2xxx, 6xxx, and 7xxx alloys can participate in the precipitation hardening process.
Method 4: Dispersion Hardening
In the dispersion hardening process, fine particles like oxides or carbides are added to the aluminum matrix. The strength of the aluminum alloy depends on the volume and size of the external particle.
Method 5: Grain Refinement (Small Grain Size)
When the aluminum alloy goes through solidification, grain-refining agents are added to it. This reduces the grain size of aluminum alloy, and as a result, more grain boundaries are created. These grain boundaries prevent dislocation movement and strengthen the aluminum alloy.
Aluminum vs Aluminum Alloy: What is the Difference?
After oxygen and silicon, aluminum is the most abundant element in the earth’s crust. The chief ore of aluminum is bauxite. So, you need to mine the earth to get aluminum. Adding different other metals to this pure aluminum is called an aluminum alloy.
| Criteria | Aluminum (pure) | Aluminum Alloy |
|---|---|---|
| Composition | Contains 99% aluminum | Aluminum, and a mixture of other elements like zinc, copper, silicone, etc. |
| Strength | Lower than aluminum alloy | High due to the addition of an alloying element |
| Weight | Very lightweight | Lightweight but a bit heavier than pure aluminum |
| Corrosion Resistance | High | High but varies based on the type of alloy |
| Heat Treatment | Can’t be heat treated | Some aluminum alloys like 2xxx, 6xxx, and 7xxx series can be heat treated |
| Cost | Cheap | Expensive |
Wrapping Up
Consider your application, strength, and load requirements before picking the right aluminum alloy. Once you have chosen one for your project, Richconn is here to help you shape and design the aluminum alloy to your desired shape. We are a leading CNC machining manufacturer in China to bring your designs to life! So, contact us ASAP!
FAQs
What does aluminum alloy look like?
Aluminum alloy usually has a silvery-white metal-like appearance. The surface of these metals is smooth and shiny.
What is the strongest aluminum alloy?
7068 aluminum alloy is one of the strongest aluminum alloys. It has a tensile strength of 710 MPa (103 KSI) and a yield strength of 683 MPa (99.1 KSI).
What is the material density of aluminum alloy?
Compared to steel (7.85 g/cm³) and titanium(4.51 g/cm³), the material density of aluminum alloy is much lower. It usually ranges from 2.68 to 2.80g/cm³. This low-density feature makes them lightweight and suitable for applications like automotive and aerospace.
Is aluminum alloy on the periodic table?
No, as aluminum alloy is not a pure element, it is not included in the periodic table. Pure aluminum is present in the periodic table, which has the periodic number 13. However, due to the addition of other elements, aluminum alloy no longer resembles pure and so is not included in the periodic table.
