Introduction to Aluminum Alloy

Aluminum alloys are highly versatile materials used in various industries, offering a remarkable combination of strength, lightweight properties, and corrosion resistance. These alloys consist of aluminum mixed with other elements such as copper, magnesium, and silicon, which enhance their performance and durability. With a wide range of applications, from aerospace engineering to automotive manufacturing, alloyed aluminum has become indispensable in modern manufacturing due to its exceptional properties and ability to meet the diverse needs of different industries.

In this article, we mainly describe aluminum alloys from several perspectives, including what aluminum alloys are, properties, types and uses, etc. On the other hand, we will also answer some frequently asked questions to give you a deeper understanding of aluminum alloys. The picture on the left shows some common aluminum alloy products that can be customized for you through our online CNC machining services.

What Is Aluminum Alloy?

An aluminum alloy is a type of alloy in which aluminum is the primary metal. It is created by combining aluminum with other elements such as copper, magnesium, manganese, silicon, tin, nickel, and zinc. These alloying elements are added in specific proportions to enhance aluminum’s mechanical and physical properties, such as strength, workability, corrosion resistance, electrical conductivity, and density. Aluminum alloys are categorized into two main types: casting alloys and wrought alloys, which are further divided into heat-treatable and non-heat-treatable categories. They find widespread use in engineering structures and components that require lightweight properties and corrosion resistance, such as in the aerospace, automotive, construction, and manufacturing industries.

When Did Aluminum Alloys Appear?

Aluminum alloys have been in use for over a century, with their development and application dating back to the late 19th century. The first significant breakthrough in aluminium alloy technology occurred in 1886 with the invention of the Hall-Héroult process, which made the large-scale production of aluminum possible. This development paved the way for further advancements in aluminum alloy research and engineering. In the early 20th century, alloys such as Duralumin gained prominence and found extensive use in the aviation industry, particularly during World War I. Since then, the understanding and utilization of aluminum alloys have continued to progress, leading to the development of a wide range of alloys with improved properties and performance. Today, aluminum alloys are widely employed in various industries, including aerospace, automotive, construction, and manufacturing, due to their desirable combination of lightweight, strength, corrosion resistance, and formability.

What Is Aluminum Alloy Made Of?

Aluminum alloys combine aluminum with various other elements, such as copper, magnesium, manganese, silicon, tin, nickel, and zinc. These alloying elements are blended in specific proportions to enhance aluminum’s mechanical and physical properties. Copper improves strength and hardness, magnesium contributes to lightweight and corrosion resistance, manganese enhances strength and workability, silicon improves casting properties, and tin, nickel, and zinc are added for specific characteristics like corrosion resistance, increased strength, or improved machinability. The specific combination and proportion of these alloying elements determine the properties and performance of the resulting aluminum alloy.

Here are examples of aluminum alloys with their respective alloying elements:

1. Aluminum-Copper (Al-Cu): The alloy known as Duralumin typically contains aluminum with copper as the primary alloying element. It offers improved strength and hardness. An example is the 2024 alloy, which contains about 4.4% copper.

2. Aluminum-Magnesium (Al-Mg): An example is the 5052 alloy, which contains aluminum alloyed with magnesium. It provides excellent corrosion resistance, particularly in marine environments.

3. Aluminum-Manganese (Al-Mn): The 3003 alloy is an example of an aluminum-manganese alloy. It offers good formability, improved strength, and excellent corrosion resistance.

4. Aluminum-Silicon (Al-Si): The 6061 alloy, commonly used in structural applications, consists of aluminum alloyed with silicon. It offers good strength, machinability, and weldability.

5. Aluminum-Tin (Al-Sn): An example of an aluminum-tin alloy is the 7178 alloy, which provides high strength and resistance to stress corrosion cracking.

6. Aluminum-Nickel (Al-Ni): The 7075 alloy is an aluminum alloy with nickel as one of its alloying elements. It is known for its high strength and excellent fatigue resistance.

7. Aluminum-Zinc (Al-Zn): An example is the 7072 alloy, which contains aluminum alloyed with zinc. It offers good formability, and corrosion resistance, and is often used in architectural applications.

What Are the Characteristics of Aluminum Alloy?

Aluminum alloys possess several notable characteristics that make them highly desirable in various applications. These characteristics include:

1. Lightweight: Aluminum alloys have a low density, making them significantly lighter than many other metals. This property is particularly advantageous in industries such as aerospace and automotive, where weight reduction is crucial for fuel efficiency and performance.

2. Strength: Aluminum alloys can offer excellent strength-to-weight ratios, allowing for the construction of lightweight yet structurally strong components. The strength of aluminum alloys can be further enhanced through alloying and heat treatment processes.

3. Corrosion resistance: Aluminum alloys naturally form a protective oxide layer on their surface, which provides resistance against corrosion. Certain alloying elements, such as copper and zinc, can further enhance the corrosion resistance of aluminum alloys, making them suitable for applications exposed to harsh environments.

4. Electrical conductivity: Aluminum alloys exhibit good electrical conductivity, making them suitable for electrical transmission and distribution applications. They are commonly used in power transmission lines and electrical wiring.

5. Thermal conductivity: Aluminum alloys have excellent thermal conductivity, allowing for efficient heat transfer. This property makes them ideal for applications such as heat exchangers, radiators, and heat sinks.

6. Formability: Aluminum alloys can be easily formed into various shapes and sizes through processes like extrusion, rolling, and forging. They exhibit good ductility, enabling complex designs and intricate detailing.

7. Recyclability: Aluminum alloys are highly recyclable without any significant loss in their mechanical properties. Recycling aluminum requires significantly less energy compared to primary production, making it an environmentally sustainable choice.

What Are the Properties of Aluminum Alloy?

There are many types of aluminum alloys. Each aluminum alloy contains different alloy components and will exhibit different properties. In the table below, we summarize some common general properties of alloy aluminum:

What Are the Physical Properties of Aluminum Alloy?

The table below lists some physical properties of aluminum alloys:

Aluminum Alloy Physical Properties Table
Aluminum AlloyDensity (g/cm³)Melting Point (°C)Thermal Conductivity (W/m·K)Electrical Conductivity (% IACS)Coefficient of Thermal Expansion (10⁻⁶/°C)
11002.76602206123
20242.86301203023
30032.76551905323
50522.76071384323
60612.75851674323
70752.84771303623
50832.75701211923
60632.75802013323
20142.85351504323
60822.75551804323
70502.84901304223

What Are the Chemical Properties of Aluminum Alloy?

The table below lists some chemical properties of aluminum alloys:

Aluminum Alloy Chemical Property Table
Aluminum AlloyComposition (%)Corrosion ResistanceWeldabilityMachinabilityAnodizing Reaction
1100Al: 99.0ExcellentExcellentExcellentGood
2024Al: 90.7, Cu: 4.5, Mg: 1.5, Mn: 0.6ModerateGoodFairGood
3003Al: 98.6, Mn: 1.2GoodExcellentGoodGood
5052Al: 97.2, Mg: 2.5GoodGoodFairGood
6061Al: 97.9, Si: 0.6, Mg: 1.0, Cu: 0.28GoodExcellentGoodGood
7075Al: 90.7, Zn: 5.6, Mg: 2.5, Cu: 1.6PoorPoorFairGood
5083Al: 95.4, Mg: 4.0, Mn: 0.7ExcellentGoodFairGood
6063Al: 98.9, Si: 0.7, Mg: 0.45GoodExcellentGoodGood
2014Al: 90.7, Cu: 4.5, Si: 0.7, Mg: 1.2PoorFairFairGood
6082Al: 97.4, Si: 0.7, Mg: 1.0GoodExcellentGoodGood
7050Al: 89.7, Zn: 6.1, Cu: 2.1, Mg: 2.0PoorPoorFairGood

What Are the Mechanical Properties of Aluminum Alloy?

The table below lists some mechanical properties of aluminum alloys:

Aluminum Alloy Mechanical Properties Table
Aluminum AlloyTensile Strength (MPa)Yield Strength (MPa)Elongation (%)Hardness (HB)
110083283023
202447032520120
30031301152040
50522151601260
60612752401295
707557050511150
50832952401095
60631651451260
201445032518120
60823102601295
705060054010160

What Is the Color of Aluminum Alloy?

The color of aluminum alloy is typically a metallic silver-gray tone. The surface appearance can vary depending on factors such as the alloy composition, surface treatment, and lighting conditions. Aluminum alloys can also be coated or anodized to achieve different colors and finishes, offering a wide range of options for aesthetic purposes. However, in its natural state, the aluminium alloy exhibits a characteristic silver-gray color.

What Does Aluminum Alloy Look Like?

In the picture below, there is an image of what aluminum alloy looks like:

Aluminum-Alloy-Look-Like-image-800x600

How Many Types of Aluminum Alloys Are There?

There are numerous types of aluminum alloys available, each with its own unique composition and specific properties. The exact number of aluminum alloy types can be difficult to determine precisely due to variations in alloying elements, tempering processes, and international standards. However, thousands of aluminum alloy formulations have been developed and categorized for various applications. These alloys are typically distinguished by their numerical designations, such as the 1xxx, 2xxx, 3xxx, and so on, in which each series represents a specific group of alloys with distinct characteristics. The Aluminum Association in the United States recognizes more than 500 standard aluminum alloy designations. It’s important to note that new alloys continue to be developed and introduced over time as research and technological advancements progress in the field of aluminum alloy manufacturing.

Below are some examples of different aluminum alloy types:

1. 1xxx Series

These alloys are almost pure aluminum, with a minimum aluminum content of 99%. They are known for their excellent corrosion resistance, high electrical conductivity, and good formability. They are often used in applications where high purity and electrical conductivity are required, such as electrical wiring and chemical equipment.

2. 2xxx Series

These alloys contain copper as the primary alloying element, along with small amounts of other elements such as manganese and magnesium. They offer good strength and high heat resistance, making them suitable for aerospace and structural applications. The 2024 and 2014 alloys are examples within this series.

3. 3xxx Series

These alloys contain manganese as the primary alloying element. They exhibit good formability, moderate strength, and excellent corrosion resistance. The 3003 alloy, for instance, is commonly used in general sheet metal fabrication and cooking utensils.

4. 4xxx Series

The primary alloy within the 4xxx series is alloy 4032, which contains silicon as the main alloying element. This series is known for its excellent thermal conductivity and low coefficient of expansion, making it suitable for applications requiring thermal management, such as heat sinks and cylinder heads in the automotive industry.

The 4xxx series alloys are also known for their good castability, making them suitable for various casting processes, including sand casting and permanent mold casting.

5. 5xxx Series

These alloys are known for their excellent corrosion resistance, particularly in marine environments. They typically contain magnesium as their primary alloying element, with small amounts of other elements such as chromium and manganese. The 5052 and 5083 alloys are widely used in marine applications, transportation, and architectural structures.

6. 6xxx Series

These alloys are heat-treatable and commonly used in structural applications. They contain magnesium and silicon as the primary alloying elements, providing good formability, moderate strength, and excellent corrosion resistance. The 6061 and 6063 alloys fall within this series and are widely used in various industries, including construction, automotive, and furniture.

7. 7xxx Series

These alloys are known for their high strength and are primarily used in aerospace and high-performance applications. They contain zinc as the primary alloying element, along with small amounts of copper, magnesium, and chromium. The 7075 alloy, for example, is popular in the aerospace industry due to its exceptional strength-to-weight ratio.

8. 8xxx Series

The 8xxx series of aluminum alloys consists of alloys that are primarily used for specialty applications. These alloys often contain lithium as the primary alloying element, which helps enhance strength, stiffness, and electrical conductivity. The 8xxx series alloys are commonly used in aerospace and defense applications where lightweight and high-performance properties are required.

9. 9xxx Series

The 9xxx series includes aluminum alloys that are used for specific applications requiring exceptional strength. These alloys are primarily used in aerospace and defense industries and are typically developed for advanced structural components and high-strength applications. The 9xxx series alloys often undergo specialized heat treatment processes to achieve their desired properties.

In addition to the numbered series, there are also aluminum alloys that fall outside the numerical designations. These include:

1. Aluminum-Lithium Alloys: These alloys contain a significant amount of lithium, which helps reduce weight while maintaining strength and stiffness. Aluminum-lithium alloys are primarily used in aerospace applications where weight reduction is critical.

2. Cast Aluminum Alloys: Cast aluminum alloys are specifically formulated for casting processes. They are designed to have good fluidity, and excellent castability, and can be modified to achieve various mechanical properties. Cast aluminum alloys are used in a wide range of applications, including automotive parts, machinery components, and architectural elements.

What Are the Limitations of Aluminum Alloy?

Aluminum alloys have many desirable properties, but they also have some limitations to consider. Here are a few limitations of aluminum alloys:

1. Lower strength compared to some other metals: While aluminum alloys offer good strength-to-weight ratios, they generally have lower strength compared to steel or titanium alloys. This can impact their suitability for applications requiring exceptionally high strength or load-bearing capacities.

2. Susceptibility to deformation: Aluminum alloys can be susceptible to deformation under heavy loads or high-stress conditions, which may limit their use in certain structural applications. However, proper design and engineering considerations can help mitigate this limitation.

3. Lower melting point: Aluminum alloys have lower melting points compared to metals like steel. This can restrict their use in applications that involve high-temperature environments or require materials with exceptional heat resistance.

4. Vulnerability to galvanic corrosion: When in contact with certain dissimilar metals in the presence of an electrolyte, aluminum alloys can experience galvanic corrosion. This can limit their use in applications where galvanic corrosion is a concern and proper protective measures need to be implemented.

5. Challenges in welding: Some aluminum alloys can be challenging to weld due to their high thermal conductivity and susceptibility to cracking.

6. Limited hardness: Aluminum alloys generally have lower hardness compared to some other metals. This can limit their use in applications where high hardness or wear resistance is essential.

Despite these limitations, aluminum alloys continue to be widely used in a broad range of industries due to their favorable properties such as low density, corrosion resistance, good formability, and excellent electrical conductivity. Many of these limitations can be addressed through appropriate alloy selection, design considerations, and surface treatments to enhance performance and mitigate potential drawbacks.

What Is Aluminum Alloy Used for?

Aluminum alloy has a wide range of applications across various industries. Here are some common uses of aluminum alloy:

1. Transportation

In the automotive industry, aluminum alloy is used to manufacture vehicle bodies and structural components. For example, the Tesla Model S utilizes an aluminum frame to reduce weight and improve range. In the aerospace industry, aluminum alloy is used to construct aircraft structures, such as the Boeing 787 Dreamliner, which incorporates aluminum alloy in its fuselage, wings, and other components to achieve fuel efficiency and enhanced performance.

2. Construction and Architecture

Aluminum alloy is commonly used in window frames and curtain walls for commercial buildings. For instance, the Burj Khalifa in Dubai, the world’s tallest building, features aluminum alloy curtain walls that provide structural integrity, durability, and aesthetic appeal. Additionally, the Sydney Opera House incorporates aluminum alloy in its iconic roof shells, offering lightweight construction and corrosion resistance.

3. Packaging

Aluminum alloy is widely used in the production of beverage cans. For example, companies like Coca-Cola and PepsiCo use aluminum cans for their beverages due to the alloy’s light weight, ability to protect the contents from light and oxygen, and recyclability.

4. Electrical and Electronics

In the electrical industry, aluminum alloy is used in overhead power transmission lines due to its high electrical conductivity. For instance, the National Grid in the UK utilizes aluminum alloy conductors for long-distance power transmission. In electronics, aluminum alloy is used in heat sinks, which help dissipate heat from electronic components, ensuring optimal performance and longevity.

5. Consumer Goods

Aluminum alloy is commonly found in consumer goods such as smartphones, laptops, and tablets. For example, Apple’s MacBook laptops utilize aluminum alloy bodies to achieve a sleek design, lightweight construction, and durability.

6. Marine Applications

In the marine industry, aluminum alloy is used for boat hulls and components due to its corrosion resistance in saltwater environments. For instance, the high-speed ferries operated by the Washington State Ferries in the United States feature aluminum alloy hulls that offer excellent strength-to-weight ratio, fuel efficiency, and corrosion resistance.

7. Renewable Energy

Aluminum alloy is used in solar panels for its lightweight nature and corrosion resistance. Solar panel frames and mounting structures are often made from aluminum alloy due to its durability and ease of installation. Wind turbine blades also utilize aluminum alloy for their lightweight construction, allowing for efficient energy generation.

8. Industrial and Machinery

Aluminum alloy is used in various industrial applications, such as in the manufacturing of machinery components and equipment. For example, CNC machines incorporate aluminum alloy parts due to their lightweight nature, high precision, and resistance to wear and corrosion.

What Is the Cheapest Aluminum Alloy?

One commonly used low-cost aluminum alloy is 1100 aluminum. It belongs to the 1xxx series and is known for its high purity and excellent corrosion resistance. 1100 aluminum has relatively low strength compared to other aluminum alloys but is often chosen for applications where corrosion resistance and formability are more important than strength. Its affordability and versatility make it widely used in general sheet metal work, appliances, chemical equipment, and lightweight applications.

What Is the Lightest Aluminum Alloy?

The lightest aluminum alloy is typically considered to be the 1000 series, specifically alloy 1050. The 1000 series alloys are known for their high purity, excellent formability, and low strength. Alloy 1050 has a density of approximately 2.7 g/cm³, which is relatively low compared to other aluminum alloys. Its low density makes it an ideal choice for applications where weight reduction is critical, such as in the aerospace industry for aircraft structures and components.

What Is the Most Common Aluminum Alloy?

The most common aluminum alloy is 6061 aluminum. It belongs to the 6xxx series and is widely used in various industries. Alloy 6061 offers a good balance of strength, formability, and corrosion resistance, making it versatile and suitable for a wide range of applications. It is commonly used in structural components, such as frames, beams, and supports in the aerospace, automotive, and marine industries. Additionally, it is utilized in consumer goods, such as bicycle frames, sporting equipment, and furniture. The popularity of 6061 aluminum can be attributed to its desirable properties, availability, and relatively low cost compared to some other aluminum alloys.

What Is the Strongest Aluminum Alloy?

One of the strongest aluminum alloys is 7075 aluminum. It belongs to the 7xxx series and is known for its high strength-to-weight ratio. Alloy 7075 is often used in applications that require exceptional strength, such as aerospace structures, high-performance bicycle frames, and rock climbing equipment. It offers excellent mechanical properties, including high tensile strength and good fatigue resistance. However, it’s important to note that the strength of an aluminum alloy can be further enhanced through heat treatment processes, such as precipitation hardening. By subjecting alloy 7075 to a precipitation hardening treatment, known as T6 tempering, its strength can be significantly increased. It’s worth mentioning that while 7075 aluminum is one of the strongest aluminum alloys, there are other alloys with varying strengths suited for specific applications.

What Are the Two Categories of Aluminum Alloys?

Aluminum alloys can be roughly divided into the following two categories:

1. Wrought Aluminum Alloys

Wrought aluminum alloys are those that are shaped or mechanically worked into their final form. This category includes alloys that are commonly used in various applications. Wrought aluminum alloys can be further classified based on their alloying elements, such as the 1xxx, 2xxx, 3xxx, 4xxx, 5xxx, 6xxx, and 7xxx series. Each series has specific properties and characteristics suited for different applications.

2. Cast Aluminum Alloys

Cast aluminum alloys are those that are melted and poured into molds to solidify their final shape. This category includes alloys that are primarily used in casting processes, such as sand casting, die casting and investment casting. Cast aluminum alloys offer good casting properties and can be tailored to specific applications by adjusting the alloy composition and casting parameters.

These two categories, wrought aluminum alloys, and cast aluminum alloys, encompass the majority of aluminum alloys used in various industries and applications. Each category has unique properties, manufacturing processes, and applications, providing a wide range of options for different engineering needs.

What Is the Difference Between Aluminum Alloy vs. Alloy?

“Alloy” is a general term that refers to a metal or a mixture of metals and non-metallic elements, while “aluminum alloy” is a specific type of alloy in which aluminum is the predominant metal in the mixture. Aluminum alloys are specially formulated to enhance the properties of aluminum and are widely used in various industries due to their good combination of strength, lightweight, corrosion resistance, and other beneficial properties.

What Is the Difference Between Aluminum vs. Alloy?

The term “aluminum” refers to a chemical element with the symbol Al and atomic number 13. It is a lightweight, silvery-white metal that is known for its low density and excellent corrosion resistance. while “alloy” is a broader term referring to a mixture of metals or a metal with non-metallic elements. “Aluminum alloy” specifically refers to a type of alloy where aluminum is the primary metal in the mixture.

Generalize

This article introduces aluminum alloys, explains its definition, and discusses its various applications and advantages. Additionally, we provide FAQs about aluminum alloys to deepen your understanding of alloy aluminum. To learn more about aluminum alloys, please contact our team.

Ruitai offers extensive manufacturing capabilities and other value-added services for all your prototyping and production needs. We can provide you with a free quote at your convenience. Welcome to contact us.

Disclaimer

Please note that the data content provided in this article is for reference only. This information is based on our current knowledge and is provided in good faith. Ruitai Mould assumes no responsibility for the completeness, accuracy, or validity of the information provided, express or implied.

Addressing Common Aluminum Alloys Questions:

Q1: Is aluminum alloy stronger than aluminum?
A1: Yes, aluminum alloy is generally stronger than pure aluminum. The addition of other elements in the alloy improves its strength and other properties.

Q2: Is aluminum alloy stronger than titanium?
A2: Titanium is generally stronger than aluminum alloy. Titanium has a higher strength-to-weight ratio, making it stronger and lighter than most aluminum alloys.

Q3: Is aluminum alloy the same as aluminum?
A3: No, aluminum alloy refers to a combination of aluminum with other elements, such as copper, zinc, or magnesium, to enhance its properties. Pure aluminum, on the other hand, refers to aluminum without any other elements.

Q4: Is aluminum alloy strong?
A4: Yes, aluminum alloy is known for its strength. The specific strength of an aluminum alloy can vary depending on its composition and heat treatment.

Q5: Is aluminum alloy magnetic?
A5: No, aluminum and aluminum alloy are not magnetic. They are non-magnetic materials.

Q6: Is aluminum alloy a metal?
A6: Yes, aluminum alloy is a type of metal. It is a lightweight and malleable material widely used in various industries.

Q7: Is aluminum a nonferrous alloy?
A7: Yes, aluminum is a nonferrous alloy. Nonferrous alloys do not contain iron as the primary metal.

Q8: Is aluminum a pure metal or an alloy?
A8: Aluminum can exist in both forms. Pure aluminum refers to aluminum without any other elements, while aluminum alloy refers to aluminum combined with other elements to enhance its properties.

Q9: Is aluminum alloy a renewable resource?
A9: Aluminum itself is not a renewable resource since it is derived from bauxite ore. However, aluminum is highly recyclable, which makes it a sustainable material choice.

Q10: Is aluminum alloy bulletproof?
A10: Aluminum alloy is not typically considered bulletproof on its own. It has a good strength-to-weight ratio but may not provide sufficient protection against high-velocity projectiles without additional reinforcement.

Q11: Is aluminum alloy cheap?
A11: Aluminum alloy is generally considered to be an affordable material compared to some other metals. Its availability and ease of extraction contribute to its relatively low cost.

Q12: Is aluminum alloy combustible?
A12: Aluminum alloy has a high ignition temperature and is generally considered non-combustible. However, it can melt under high heat and may contribute to the combustion of nearby flammable materials.

Q13: Is aluminum alloy ferrous?
A13: No, aluminum alloy is not ferrous. Ferrous materials contain iron as the primary metal component, while aluminum alloy does not.

Q14: Is aluminum alloy a high melting point or low mass?
A14: Aluminum alloy has a relatively low melting point compared to some other metals. However, it also has a low density, which means it has a low mass for a given volume.

Q15: Is aluminum alloy recyclable?
A15: Yes, aluminum alloy is highly recyclable. It can be melted down and reused without significant loss of quality, making it a sustainable material choice.

Q16: Is aluminum alloy resistant to acid?
A16: Aluminum alloy has limited resistance to certain acids. It can react with strong acidic substances, such as hydrochloric acid or sulfuric acid, leading to corrosion or damage.

Q17: Are aluminum alloys corrosive?
A17: Aluminum alloys are generally resistant to corrosion due to the formation of a protective oxide layer on the surface. However, certain conditions or corrosive environments can still cause corrosion to occur.

Q18: Can an aluminum alloy rust?
A18: No, aluminum alloy does not rust. Rust is a term specific to iron and steel corrosion. However, aluminum alloy can corrode under certain conditions, resulting in the formation of a different type of corrosion product.

Q19: Does aluminum alloy bend?
A19: Yes, aluminum alloy can be bent and formed into various shapes. Its malleability allows for easy deformation without the material breaking.

Q20: Does aluminum alloy conduct electricity?
A20: Yes, aluminum alloy is a good conductor of electricity. It is commonly used in electrical applications due to its high electrical conductivity.

Q21: Does aluminum alloy contain lead?
A21: Aluminum alloy does not typically contain lead as one of its primary elements.

Q22: Does aluminum alloy contain nickel?
A22: Aluminum alloy can contain nickel as one of its alloying elements, depending on the specific composition. However, not all aluminum alloys contain nickel.

Q23: Does aluminum alloy tarnish?
A23: Aluminum alloy can develop a tarnish or dull appearance over time due to exposure to air and moisture. However, the formation of a thin oxide layer on the surface can provide some protection against further corrosion.