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The Physical Properties of Aluminum


With aluminum being such an indispensable part of our lives, it might seem like this wonder metal has always been around. The truth is that aluminum’s use in manufacturing and industry has a short history, barely more than a century. This is because for most of human history, we did not even know that aluminum existed.

Despite being the third most abundant element in the Earth’s crust, aluminum is hard to find. In its purest form, aluminum is highly reactive and easily bonds to other minerals, meaning that it is extremely rare. Instead, it is an integral ingredient of common ores such as alum and bauxite.

After several centuries of discovery, scientists were finally able to isolate pure aluminum in the 1800’s. It took another several decades to come up with a commercially viable method of extracting aluminum for industrial purposes. That is why it wasn’t until the early twentieth century that this metal became readily available.

Once technology unlocked the secret of producing aluminum alloys on a large scale, it did not take long for it to begin transforming all kinds of industries. From aviation to medicine, and everything in between, aluminum’s amazing properties make it one of the most important materials in use today. In today’s post, we will be looking at these properties and hopefully you will gain a better idea of why aluminum is so special.

What is aluminum?

The first thing you need to know about aluminum is that it is the 13th element on the periodic table and has the atomic symbol of Al. In its natural form, it is a silvery-white, non-magnetic, ductile metal. According to mass, it accounts for 8% of the Earth’s crust, making it the most abundant metal in existence.

Aluminum’s appearance can vary depending upon its surface finish. A polished aluminum surface can reflect about 92% of visible light. It is also useful for reflecting medium and far infrared radiation.

Most commercial grades of aluminum have a density of 0.0975 lb/in³. Compared to steel, that is about one third as dense. This is because an aluminum nucleus is much lighter without being appreciably smaller. In practicality, the only metals that are lighter than aluminum are from group 1 and 2, which for the most part are far too reactive for structural use. The lone exceptions are beryllium and magnesium.

It’s all about the weight

If you only had to focus on one property of aluminum as its most essential, most people would agree on its light weight. This, combined with its relatively high strength, is what makes aluminum such a key material in nearly every commercial industry you can think of.

While pure aluminum lacks the durability needed in some high performance fields, when alloyed with other elements, it becomes extremely strong. While not as strong as steel, being a third of the weight means that aluminum can be used in all sorts of applications where weight is of critical concern. As an added benefit, aluminum’s tensile strength increases as temperatures decrease without any loss of toughness, whereas steel becomes more brittle under similar conditions.

Don’t forget about its corrosion resistance

Aluminum’s reactivity might at first glance seem like a difficult obstacle to overcome, but it is the main reason why aluminum is so highly resistant to corrosion. When exposed to oxygen, aluminum will naturally produce what is known as a passivation layer. This is a thin surface layer of aluminum oxide, a form of oxidation and the same process that leads to rust in iron.

However, in aluminum, this layer of aluminum oxide protects the metal from further corrosion. In fact, if the metal is scratched or otherwise damaged, it will quickly repair itself through passivation.

It should be noted that some aluminum alloys do not easily form an oxide layer, making them more susceptible to corrosion. Thankfully, there are methods for enhancing the oxidation, such as anodizing, chromate conversion coating or rinsing the metal with a solution of nitric acid, peroxide and deionized water.

On the other hand, several alloys have been developed that enhance aluminum’s natural corrosion resistance, making it suitable for extreme environments, such as seawater or where toxic chemicals are present.

Aluminum has plenty of other beneficial properties

If that were all the positive attributes of aluminum, it would not be so ubiquitous today. Aluminum is a highly versatile metal, meaning it can be adapted to all kinds of applications. This starts with aluminum’s excellent formability. Because of its ductility, aluminum can be fabricated in a variety of ways, while its tensile strength and durability mean that it is still able to retain its natural resilience. That is why you see the great variety in all manner of aluminum parts.

Another positive attribute of aluminum is its excellent thermal conductivity. It is frequently used as a heatsink for a variety of devices such as LED lights, computers, mobile phones and electrical products. Aluminum also compares favorably to copper in terms of electrical conductivity. While it is not quite as conductive as copper, because it is 1/3 the weight of copper only half the weight of aluminum wire is required to conduct the same amount of electricity, making it a proven option for transmission lines.

Other benefits include aluminum’s reflectivity (as previously mentioned) and aesthetic appearance, making it suitable for architectural and engineering solutions. Aluminum is also easily recycled, is non-toxic, and has many other advantages in terms of sustainability. It is both odorless and impermeable, and offers excellent hygienic properties, which helps explain why it is so important to the food and beverage, medical device and chemical industries.

Your Technical Services Professional

There is one last advantage of aluminum that should be mentioned. A diverse set of alloys are available that can fit almost any application. In fact, there are so many alloys to choose from, it can be tough to know which one is the best option. That is why working with a proven material supplier is a must.

At Clinton Aluminum, our team of technical professionals is committed to working with our customers through every step of the procurement process. Contact one of our experienced and knowledgeable customer services representatives today.


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