What is aluminum? Is aluminum an alloy?
Aluminum (Al) is a silvery-white metallic element found abundantly in the earth’s crust (8.23%). Its affinity for oxygen restricts its availability in the free state. Commonly, it exists as silicates – bauxite and cryolite. Bauxite, the most prevalent source of aluminum, is extracted from open pit mines and processed into alumina through the Bayer process.
In contrast, an alloy combines two or more elements, one of which must be a metal, to boost chemical properties like strength and stiffness. An Al alloy contains aluminum with copper, magnesium, silicon, etc.
So, aluminum is a pure chemical element with a metallic structure. Alloys contain atomic components from different elements.
How strong is an aluminum alloy?
The strength depends on the constituents in the aluminum alloy, categorized from 1xx to 8xxx depending on the additives. Pure aluminum is soft, and its sturdiness increases with alloying.
The strongest alloys are the zinc grades (7xxx). Tennalum 7068 is the commercially available aluminum alloy with the highest yield strength of 683 MPa.
Is aluminum different from aluminum alloy?
Alloyed aluminum gets produced by putting additives in controlled conditions and amounts. For example, while the 1xxx series uses 99% (or higher) aluminum, 2xxx uses copper for strength and hardness. The alloys from 3xxx to 7xxx lineups use manganese, silicon, magnesium, silicon-magnesium, and zinc, respectively. Over 100 aluminum alloys work across industries, with some containing strontium and phosphorous.
In comparison, aluminum is an individual chemical element, soft and lightweight.
The density of aluminum and its Alloys
Aluminum is a light metal having a density of just 2710 kg per m3. A typical aluminium alloy maintains this property, ranging from 2600 to 2810 kg/m3 (approx.).
In which condition should you buy this material?
Aluminum alloys display superior strength over pure aluminum – up to 30 times or more. Buyers can purchase wrought alloys for applications demanding excellent ductility, like wiring and automotive parts. Casting alloys, comparatively inexpensive, work in structural machinery and engine parts. But they have lower tensile strengths and melting points, limiting usability.
Further, industries can choose between heat-treatable (heated and quenched) and non-heat-treatable alloys. The latter gets strengthened through cold working.
How can you select the right grade for electrical conductivity?
Pure aluminum has an electrical conductivity of 237 W m−1 K−1. Its alloys have lower conductivity than the pure aluminium material. Applications that need top-notch electrical properties, like overhead power lines and electric busbars, often turn to the 6xxx series.
While selecting the alloy, buyers should consider the temperature, strain, and pressure.
Qualities and Advantages
- Lightweight and versatile – This light strong metal shows a low density and good strength for its weight.
- Incredibly corrosion resistant – An oxide layer on the surface helps commercially pure aluminum resist corrosive attacks in a pH range of 4.5 to 8. (This property diminishes with alloying.)
- Eco-friendly project solution – This metal can get fully recycled at a reasonable cost without compromising metallurgical properties.
- Excellent thermal and electrical properties – Aluminum is a good conductor of heat and electricity, with a thermal expansion coefficient equaling 23.2.
- Malleable & formable – Malleability allows these alloys to get shaped based on project requirements.
The lightweight strength of an aluminum alloy makes it ideal for aerospace, manufacturing, construction, and marine applications. Its electrical properties suit power transmission, circuit breaker contacts, and satellite dishes.
Series 5xxx alloys work in formable automotive sheets, boats, and shipping containers. Aluminum and its alloys work in wind and solar energy management and transportation. Alloy 3003 is among the best for bending, often used in chemical equipment.
Creating alloys with aluminum is rewarding because the process elevates the characteristics of the metal. Alloys can get produced by heating the metal over its melting point and adding the components to the molten liquid. Solid or gaseous state diffusion also gets utilized for some metals. For instance, Birmabright combines aluminum with magnesium and Silumin with silicon.
Aluminum vs aluminium can get confusing, but they refer to the same material. “Aluminum” is the preferred spelling in America, but “Aluminium” is favored in Europe.
Understanding the difference between aluminum and its alloys and selecting the appropriate material for your application is critical for long-term performance.