Types of Aluminum materials:
- Pure Aluminum
- Aluminum-Copper Alloys
- Aluminum-Manganese Alloys
- Aluminum-Silicon Alloys
- Aluminum-Magnesium Alloys
- Aluminum-Magnesium-Silicon Alloys
- Specialty Alloys
Aluminum alloy is a metallic material formed by adding one or more alloying elements such as copper, magnesium, silicon, zinc, manganese, etc. to aluminum (Al) as the base element.
As the most widely used non-ferrous metal structural material in industry, its usage volume is second only to steel.
It features light weight, high strength, corrosion resistance and other characteristics, and is one of the most popular alloy materials in modern industry.
The core definition and composition of aluminum alloys
The proportion of aluminium is usually ≥90%, and the rest are alloying elements:
- Main elements
- Trace elements
- Alloying principle
Main elements
Copper (Cu), magnesium (Mg), silicon (Si), zinc (Zn), manganese (Mn), used to enhance strength, hardness or heat resistance.
Trace elements
Nickel (Ni), titanium (Ti), chromium (Cr), lithium (Li), etc., are used to refine grains or enhance specific properties.
Alloying principle
Through mechanisms such as solid solution strengthening and precipitation hardening, it overcomes the defect of low strength of pure aluminum tensile strength about 90MPa.
Pure Aluminum
Composition: Al ≥99.00% (e.g., 1050, 1070, 1100).
Properties:High conductivity (61% IACS) and thermal conductivity.
Excellent corrosion resistance due to natural oxide layer.
Low strength (σb: 80–110 MPa), high plasticity.
Applications:Electrical cables, heat sinks, food packaging, and decorative panels.
Aluminum-Copper Alloys
Composition: Cu (3–5%) as main alloying element.
Properties:High strength (σb >400 MPa after heat treatment).
Poor corrosion resistance; prone to intergranular corrosion.
Applications:Aircraft structures (wing beams, landing gear), high-stress automotive parts.
Aluminum-Manganese Alloys
Composition: Mn (1.0–1.5%).
Properties:Moderate strength (σb: 200–300 MPa), excellent formability and weldability.
Superior corrosion resistance in humid/chemical environments.
Applications:Building facades, beverage cans, heat exchangers, and vehicle bodies.
Aluminum-Silicon Alloys
Composition: Si (4.5–13.5%) (e.g., 4032, 4047).
Properties:Low thermal expansion, high wear resistance, and excellent fluidity for casting.
Heat resistance up to 400°C.
Applications:Engine pistons, welding wire, and electronic encapsulation.
Aluminum-Magnesium Alloys
Composition: Mg (3–5%) (e.g., 5052, 5083).
Properties:Exceptional corrosion resistance in marine environments.
Medium strength (σb: 200–300 MPa), lightweight (density: 2.68 g/cm³).
Applications:Ship hulls, offshore platforms, pressure vessels, and automotive fuel tanks.
Aluminum-Magnesium-Silicon Alloys
Composition: Mg + Si forming Mg₂Si precipitates (e.g., 6061, 6063).
Properties:Heat-treatable for high strength (σb: 240–280 MPa after aging).
Good machinability and surface finish for anodizing.
Applications:Architectural profiles, bicycle frames, and automotive chassis.
Aluminum-Zinc-Magnesium Alloys
Composition: Zn + Mg + Cu (e.g., 7075, 7050).
Properties:Ultra-high strength (σb >500 MPa), excellent fatigue resistance.
Poor corrosion resistance; requires coatings for harsh environments.
Applications:Aircraft fuselages, rocket components, and high-stress sports equipment.
Specialty Alloys
- Lithium-Aluminum Alloys
- Casting Alloys
Lithium-Aluminum Alloys
Properties: Reduced density (−3% per 1% Li), high stiffness.
Applications: Aerospace structures to reduce weight.
Casting Alloys
Al-Si (e.g., A356): Excellent castability, used for engine blocks.
Al-Mg (e.g., 508.3): High strength and corrosion resistance for marine components.
Processing: Suited for die-casting, sand casting, and low-pressure molding.
Aluminum Composites
Reinforcements: Carbon fiber, SiC particles.
Properties: 20–50% higher strength than base alloys.
Applications: Brake rotors, aerospace brackets.
What are the specific influence mechanisms of different alloying elements in aluminum alloys on the material properties?
The specific influence mechanisms of different alloying elements such as copper, magnesium.
And zinc in aluminum alloys on material properties can be analyzed from multiple aspects.
Including strengthening mechanisms, phase transformation, solid solution strengthening, grain refinement, and stress corrosion tendency, etc.
The influence mechanism of copper (Cu)
Copper in aluminum alloys mainly enhances the strength and hardness of the alloys through solid solution strengthening and aging strengthening.
The addition of copper can enhance the tensile strength and hardness of aluminum alloys, but it will reduce their corrosion resistance and plasticity.
The copper content is usually between 2.5% and 5%, and the strengthening effect is the best when the content is between 4% and 6.8%.
The addition of copper can also promote precipitation hardening and enhance the strength of the alloy.
The influence mechanism of magnesium (Mg)
Magnesium is an important strengthening element in aluminum alloys, mainly enhancing the strength of alloys through solid solution strengthening and precipitation strengthening.
The addition of magnesium can significantly enhance the tensile strength and machinability of aluminum alloys, but excessive magnesium can lead to increased brittleness.
Magnesium combines with silicon to form the Mg2Si phase, further strengthening the alloy.
The addition of magnesium can also enhance the weldability and corrosion resistance of aluminum alloys.
The influence mechanism of zinc (Zn)
Zinc in aluminum alloys mainly enhances the strength of the alloys through solid solution strengthening and precipitation strengthening.
Zinc alone added to aluminium has a limited effect on enhancing strength, but when combined with magnesium (such as in Al-Zn-Mg alloys), it can significantly increase strength.
However, there is a tendency for stress corrosion cracking (SCC).
The addition of zinc can also improve the heat treatment performance of aluminum alloys, but excessive zinc may lead to stress corrosion cracking.
