Magnesium: Definition, Composition, Properties, and Applications
Dive deeper into the world of magnesium and find out more about what it is, its properties, structure, and uses.
Magnesium alloys are known for their amazing strength-to-weight ratios, regardless of whether they are cast or wrought, and so this makes them extremely useful and appealing for many engineering applications. Compared to other materials Xometry offers, such as stainless steel and aluminum, magnesium can be up to 70% and 33% lighter respectively. In the world of structural metals, magnesium alloys do not only have the highest damping capacity, but they’re also cost-effective and very easy to work with.
This is why they’re commonly used in industries such as aerospace, automotive, electronic, defense, biomedical, green energy technologies, and manufacturing. Let’s take a look at everything to do with magnesium, including its composition, applications, chemical and physical properties, and advantages and limitations, to name a few. So, let’s get right to it.
What is Magnesium?
Magnesium (Mg), atomic number 12 on the periodic table, is a silvery-white alkaline earth metal that looks a little like aluminum and is solid and quite dense at room temperature. It got its name from Magnesia, a region in Greece’s Eastern Thessaly. At first, magnesium was mainly recognized through compounds like Epsom salts (magnesium sulfate), magnesia or magnesia alba (magnesium oxide), and magnesite (magnesium carbonate).
It’s the eighth most abundant metal on Earth, making up around 2.4% of the Earth’s crust. With a density of only 1.74 g/cm3, magnesium is considered the lightest structural metal. It only consists of magnesium atoms, and each atom has 12 protons in its nucleus, with each of them having a corresponding number of electrons orbiting around the nucleus.
Looking closer at its formation, magnesium has a hexagonal close-packed (hcp) crystalline arrangement. Like other metals with the same structure, magnesium is less malleable in lower temperatures when it’s being processed. Interestingly, when it’s in its pure form, it doesn’t possess enough strength for most structural applications. That’s why it’s often alloyed with other elements to improve its mechanical properties and make it fantastic for situations that require a light, yet durable material. The automobile, electronics, and aerospace sectors are all examples of industries that love to use magnesium alloys.
Regarding magnesium’s silvery-white color, this is only the case when it’s freshly exposed. Over time, when it’s exposed to air, it can develop a more gray color because of the thin layer of magnesium oxide that tends to form on the surface. Sometimes, the color can vary even more depending on the composition and surface treatment.
What Is the History of Magnesium?
Magnesium made its first appearance way back in 1808, when Sir Humphrey Davy, a British chemist, passed electricity through a mixture of magnesium sulfate and mercury and then heated the mixture in order to remove the mercury and only leave the magnesium behind. Then, 20 years later, French scientist Antoine Bussy was able to produce the first metallic magnesium by reducing melted magnesium chloride with potassium vapor.
In 1833, there was further development when Michael Faraday, a scientist from England, made magnesium from the electrolysis of molten magnesium chloride. He did so well with this experiment that it was later replicated by German chemist, R. Bunsen. By 1886, magnesium was getting ready for industrial-scale production, thanks to the company Aluminium und Magnesiumfabrik Hemelingen based in Germany.
Fast-forward to the 1920s and 1930s, this company had become well-established in the magnesium production sector, especially when it came to the IG Farben process, which allowed them to produce large amounts of almost water-free magnesium chloride, and electrolyze it in order to extract chlorine and magnesium metal.
What Is the Other Term for Magnesium?
Magnesium is often referred to by its chemical symbol, "Mg." The name originates from Magnesia, a region situated in Eastern Thessaly, Greece. Initially, magnesium was recognized primarily through compounds such as Epsom salts (magnesium sulfate), magnesia or magnesia alba (magnesium oxide), and magnesite (magnesium carbonate). The silvery-white element in its pure form is not found in nature.
What Is Magnesium Made Of?
Magnesium is a chemical element with the symbol "Mg" and atomic number 12 on the periodic table. It is an elemental metal, which means that its composition consists solely of magnesium atoms. Each magnesium atom has 12 protons in its nucleus and a corresponding number of electrons orbiting around the nucleus.
How Is Magnesium Processed?
You won’t be able to find pure magnesium in nature, so obviously, it has to be produced by specialized chemical processes. The main places where magnesium can derive from are seawater and natural brines, which have approximately 1.3 kg/m3 of dissolved magnesium, and minerals like magnesite and dolomite.
A lot of energy is required in order to extract magnesium from raw source materials. The first step is to concentrate the source material into a form that can be used in one of the two following methods: the thermal reduction method, also called the Pidgeon process, or the electrolytic process. Let’s take a closer look at each of these.
Pidgeon Process
The Pidgeon process requires dolomite ore to be crushed and heated in a kiln, which produces a mix of magnesium and calcium oxides. After being combined with crushed ferrosilicon, this blend is made into briquettes, which are then heated in a vacuum until the silicon in the ferrosilicon has reduced the magnesium oxide to magnesium.
The process needs to be done at a temperature above magnesium’s vaporization temperature for a good result. When it’s finished, the pure element is collected as a gas, and then it’s condensed, cooled, and cast into ingots. The pigeon process can produce magnesium at a purity of up to 99.99%, which is slightly higher than the electrolytic processes, which we’ll dive into right now.
Electrolytic Process
The electrolytic process is broken down into two parts:
- Obtaining pure magnesium chloride from seawater or brine. This first step requires the treatment of seawater or brine with calcined dolomite, which produces magnesium hydroxide. This newly produced Mg(OH)2 is then converted into oxide. The oxide is then heated with carbon with some chlorine present, and this is carried out in an electric furnace at a high temperature.
- Electrolysis of fused magnesium chloride is the second step. When step one has been completed and fused anhydrous magnesium chloride has been produced, it’s then fed into electrolytic cells and melted in order to conduct electricity.
After the process has been completed, the molten magnesium is cast into ingots, and the chlorine gas is recycled into the chlorination furnace. After the electrolytic process has been done and magnesium has been extracted, it’s usually processed even more and used as an alloying element.
What Are the Characteristics of Magnesium?
Before using magnesium in any particular project, it’s good to know its key characteristics. We’ve compiled a list of them below, which primarily apply to pure magnesium, unless stated otherwise.
- Low density
- Highly flammable
- Susceptible to oxidation and corrosion
- Decent electrical conductivity
- Can be used in conjunction with other elements to form various alloys
- Excellent strength-to-weight ratio (especially in magnesium alloys)
- Great thermal conductivity (even when alloyed)
- Easy to cast (especially when alloyed)
- Biodegradable and biocompatible
- Fairly soft and pliable (can vary depending on each specific alloy structure)
What Is the Color of Magnesium?
Freshly exposed surfaces of pure magnesium have a silvery-white color, similar to many other metals. However, over time, when exposed to air, magnesium can develop a dull gray patina due to the formation of a thin layer of magnesium oxide on its surface. This oxide layer can give magnesium a slightly grayish appearance. Additionally, magnesium alloys can vary in color depending on their composition and surface treatment.
What Does Magnesium Look Like?
Magnesium is solid at room temperature and has a solid, dense texture. Pure magnesium typically appears as a shiny, silvery-white metal when freshly cut or polished. It has a metallic luster and reflects light in a manner similar to other metals.
What Are the Physical Properties of Magnesium?
Moving on to the physical properties of magnesium, some of which we’ve briefly covered in previous parts of this article, we’ve put together the following table which provides further information on each property.
| Property | Value/Description |
|---|---|
Property Color | Value/Description Silvery-white |
Property Density | Value/Description 1.74 g/cm^3 at 20 °C |
Property Brinell hardness | Value/Description 30 |
Property Tensile strength | Value/Description up to 280 MPa (cast alloys), up to 360 MPa (wrought alloys), up to 20 MPa (pure cast) |
Property Yield strength | Value/Description up to 160 MPa (cast alloys), up to 300 MPa (wrought alloys), up to 20 MPa (pure cast) |
Property Young’s Modulus | Value/Description 44-45.5 GPa |
Property Ductility | Value/Description 0.12-0.2 |
Property Poisson’s Ratio | Value/Description 0.28-0.295 |
Property Melting point | Value/Description 650 °C (alloys will have different values) |
Property Boiling point | Value/Description 1107 °C (alloys will have different values) |
Property Flammable | Value/Description Yes |
Property Electrical conductivity | Value/Description 2.3×107 S/m |
Property Corrosion resistance | Value/Description Poor |
Property Thermal conductivity | Value/Description 156 W/mK |
Physical Properties of Magnesium
| Property | Value/Description |
|---|---|
Property Atomic number | Value/Description 12 |
Property Atomic mass | Value/Description 24.30 g/mol |
Property Atomic radius | Value/Description 0.160 nm |
Property Structure | Value/Description hexagonal close-packed (HCP) crystal structure in pure form |
Property Isotopes | Value/Description 3 natural isotopes with mass numbers 24,25 and 26 |
Property Valence electrons | Value/Description 2 |
Property Recyclable | Value/Description Yes |
Chemical Properties of Magnesium
What Are the Applications of Magnesium?
Magnesium has so many different uses and is commonly found in many applications, a few of which we’ve listed below.
Pyrotechnics
When burned, magnesium produces an intense bright, white light, so it’s often used in fireworks and flares. It’s an incredible way to enhance the visual effects of pyrotechnic displays.
Luggage
Magnesium’s great strength-to-weight ratio has made it a popular go-to for the manufacturing of luggage, with many high-end brands using magnesium alloys for their lightweight yet durable suitcase frames.
Sports and Recreation Equipment
You’ll often see sports equipment like tennis rackets, golf clubs, and bicycle frames made from magnesium alloys. That’s because its ability to provide durability and stiffness despite its lightweight makes it very appealing to athletes and sports companies alike.
Cameras
Cameras, especially high-end modular cameras, can get very heavy and require careful handling because of their sensitive nature. That’s why magnesium is often used in the production of camera bodies, to keep them as light as possible, while making them more durable.
Power Tools
Power tools are often made from magnesium in order to keep them light and resistant to heavy impact. Another impressive feature of magnesium is that it can actually dampen vibrations, making it ideal for use in power tools.
Car Seats
Especially important in sports cars, car seats need to be durable but not weigh the car down with unnecessary weight. That’s where magnesium comes in handy—often used by car manufacturers for the construction of seat frames.
Laptops
Depending on how you’re reading this article, you may be holding some magnesium right now. Laptop casings are often made using magnesium, especially high-end models, because of important benefits like its strength, weight, and heat dissipation properties.
Why Magnesium Is Used in Stainless Steel?
Magnesium is a crucial component in the production of steel, primarily due to its role in desulfurization. Sulfur is typically considered an unwanted impurity in steel rather than an intentional alloying element. Sulfur, when present in steel, can have detrimental effects on its mechanical properties. It is also regarded as detrimental to both the surface and internal quality of steel. With concentrations exceeding 0.05%, sulfur can lead to increased brittleness and reduced weldability of steel. Besides making steel more brittle, it plays a role in reducing its melting point and diminishing its intergranular strength and cohesion. Also, in the presence of elemental sulfur, steel can experience both general and localized forms of corrosion. However, intentionally adding small amounts of sulfur, typically ranging from 0.10% to 0.30%, can actually enhance the steel's machinability.
Magnesium can reduce the sulfur content of steel to extremely low levels, as little as 0.0002%.
Why Is Magnesium Not Used in the Building Industry?
Magnesium is not used in the building industry because magnesium and its alloys are prone to galvanic corrosion, particularly when exposed to moisture and corrosive agents prevalent in construction environments. This susceptibility to corrosion raises durability concerns for long-term structural integrity. Moreover, the cost of producing magnesium and its alloys can be relatively high compared to established building materials like steel or aluminum.
Can Magnesium Be Used in Die Casting?
Yes, magnesium can be used in die casting. Pure magnesium is not used, but magnesium alloys such as AZ91D are very popular die casting material choices. This alloy has castability and toughness, rendering it a good choice for crafting lightweight components with sufficient ductility that demand lasting performance. Other common magnesium die casting alloys include: AM60B, AM20, and AM50A.
Magnesium die casting designs can incorporate thin walls in regions where strength isn't a critical factor, and sturdier walls in zones necessitating heightened strength. The high-pressure die casting process enables the production of thinner walls with magnesium (ranging from 1 to 1.5 mm) than with aluminum alloys (typically around 2 to 2.5 mm).
What Are the Benefits and Limitations of Magnesium?
The easiest way to compare magnesium’s benefits to its limitations is to list them side-by-side, and so that’s exactly what we’ve compiled in the table below.
| Benefits | Limitations |
|---|---|
Benefits Lightest structural metal, with a weight advantage of around 30% over aluminum, and 50% over titanium | Limitations Highly flammable—especially in its pure form—but this is not as bad when it’s in bulk form as opposed to powder or shaved strips |
Benefits Cost-effective option because it’s easy to find | Limitations Without the use of corrosion-resistant alloys, it can be more prone to corrosion than other metals like aluminum and stainless steel |
Benefits Incredible strength-to-weight and stiffness-to-weight ratios | Limitations Processing magnesium can be quite complex when compared to processing other metals |
Benefits Great thermal conductivity | Limitations Some magnesium alloys can be brittle, especially at low temperatures |
Benefits Excellent for electromagnetic shielding in aerospace and electronics applications | Limitations Though it’s easy to find, extracting and refining magnesium can consume a lot of energy |
Benefits Offers great corrosion resistance when engineered | Limitations Susceptible to galvanic corrosion, especially in the presence of an electrolyte |
Benefits Doesn’t require a lot of energy to recycle | Limitations The processing and production process can get more expensive than it would for other metals like aluminum and steel |
Benefits Has the highest known damping capacity among structural metals | Limitations Because of its low melting point, it’s not great for applications that need true high-temperature performance |
Benefits Easy to alloy with other metals and elements | Limitations - |
Benefits Some magnesium alloys are biocompatible and can be used for implants and medical devices | Limitations - |
Benefits Certain magnesium compounds are flame-retardant and useful in applications requiring fire safety | Limitations - |
Benefits When used in contact with other metals (especially in the presence of an electrolyte) it can protect the other metals from galvanic corrosion | Limitations - |
Magnesium—Benefits vs. Limitations
Frequently Asked Questions About Magnesium
Is Magnesium Rust Proof?
No. “Rusting" is a term that is applied only to the corrosion of iron and steel, whose iron oxide is less dense than the metal itself, and therefore is not tightly adherent or protective. However, both magnesium and its alloys are susceptible to galvanic corrosion, a process that can lead to significant deterioration in the metal. This is especially true in applications where magnesium is exposed to aqueous solutions. This corrosion can lead to diminished mechanical strength and undesirable visual deterioration. In contrast to the reddish-brown rust commonly seen on corroded iron surfaces, magnesium corrosion typically manifests as a subdued gray film. For this reason, magnesium is commonly used as a sacrificial anode, where magnesium corrodes to protect the other metals.
Is Magnesium Alloy?
Yes, magnesium can form alloys. An alloy is a mixture of two or more elements, at least one of which is a metal. It has properties distinct from those of its individual components. Magnesium can alloy with various other elements, such as: aluminum, zinc, and manganese. These alloying elements are added to magnesium to create magnesium alloys that exhibit specific properties tailored for various applications. Among the most common cast magnesium alloys, you'll find: Elektron 21, ZE41, QH21, HK31, ZC63, ZK61, AM50, AZ91, AZ81, AZ63, HZ32, QE22, WE54, WE43, and ZK51. On the wrought magnesium alloys side, the frequently used ones are: ZC71, ZE41, HM21, Elektron 675, ZK60, AZ80, HK31, M1A, AZ61, and AZ31.
Is Magnesium a Metal?
Yes, magnesium is a chemical element classified as an alkaline earth metal. Magnesium has the characteristic properties of metals, such as: metallic luster, high thermal and electrical conductivity, malleability (ability to be shaped without breaking), and ductility. It's an important industrial metal and has applications in fields ranging from the aerospace industry to the automotive, due to its lightweight and strong properties.
Is Magnesium a Solid, a Liquid, or Gas?
Magnesium is a solid at room temperature and normal atmospheric pressure. It is a metallic element with a silvery-white appearance. Like many other elements, magnesium can exist in different states under different conditions and different temperatures and pressures. However, under typical conditions found on Earth's surface, magnesium is solid.
What Is the Difference Between Magnesium and Metal?
Magnesium is one of the metallic elements, meaning it falls under the broad category of metals. Metals are a group of elements characterized by their metallic luster, ability to conduct electricity, and generally high melting and boiling points. Besides being a metal, magnesium is also classified under the group alkaline earth metals. They are found on the left side of the periodic table.
What Is the Difference Between Magnesium and Aluminum?
The primary difference between magnesium and aluminum lies in their densities. Magnesium boasts a lower density than aluminum, which contributes to its lighter weight for a given volume of material. Moreover, magnesium has lower melting and boiling points when contrasted with aluminum.
How Xometry Can Help
At Xometry we are used to creating parts in a variety of materials, and magnesium is no exception. While we currently don't support auto-quoting of the material and it's alloys, we are happy to manually review any projects you have which may require it. We can produce magnesium parts through our CNC machining and die casting services. To get started, simply upload your designs to the Xometry Instant Quoting Engine®. From the list of materials, you can select "Other" and write in the specific alloy you are interested in getting a quote for.
Disclaimer
The content appearing on this webpage is for informational purposes only. Xometry makes no representation or warranty of any kind, be it expressed or implied, as to the accuracy, completeness, or validity of the information. Any performance parameters, geometric tolerances, specific design features, quality and types of materials, or processes should not be inferred to represent what will be delivered by third-party suppliers or manufacturers through Xometry’s network. Buyers seeking quotes for parts are responsible for defining the specific requirements for those parts. Please refer to our terms and conditions for more information.