Aluminum’s Rise: From Luxury Metal to Industrial Mainstay
Some metals have evolved over time from rarity to a commodity. This is definitely the case with aluminum, which was discovered in its metal form only in 1825, despite being the most abundant metal in the Earth’s crust, even more common than iron.
The difference with iron is that aluminum is extremely difficult to refine, requiring extremely high temperatures. As a result, it was initially more precious than gold, and used only as a luxury metal for jewelry and cutlery.
Napoleon is reputed to have held a banquet where the most honored guests were given aluminum utensils while others made do with gold.
As better industrial processes were invented, it became the go-to metal for corrosion-resistant applications, as well as anything where light weight plays a key role, like automotive and aerospace applications. Today it is also a popular metal for 3D printing applications.
Still, more improvements can likely be made to aluminum alloys, thanks to better nanoscale structures.
This is what researchers working at the Xi’an Jiaotong University, Shanghai Jiao Tong University, Lanzhou University, Shandong University, Hebei University of Technology, Kyushu University (Japan), Imperial College (UK), and the Max Planck Institute (Germany) discovered.
They developed a new type of aluminum alloy with a 40% increase in strength and fivefold increase in resistance to hydrogen, opening the way for new applications for aluminum in a future hydrogen economy.
They published their findings in the prestigious review Nature1, under the title “Structurally complex phase engineering enables hydrogen-tolerant Al alloys”.
The Role of Aluminum in a Future Hydrogen Economy
As soon as mankind figured out how to produce high enough temperatures for smelting aluminum, it became a very important industrial metal. This is because it is simultaneously lightweight, strong, and corrosion-resistant.
Source: Erect a Step
It is also superior to steel in terms of machinability, or the ease of processing it with machine tools.
Lastly, aluminum is a much better conductor of heat and electricity, and is actually the metal used in high-tension power lines, with copper only used for the local electrical connections.
It is also commonly used in pipes and tanks. However, it does not perform well in this role when it comes to storing and transporting hydrogen. When exposed to hydrogen, it suffers a process called “embrittlement,” leading to cracking and failure.
Understanding Hydrogen Embrittlement in Metals
Hydrogen embrittlement is a phenomenon that results from metal absorbing hydrogen atoms, reducing the ductility of the metal or its ability to bend before cracking.
It occurs in steels, iron, nickel, titanium, cobalt, and their alloys. Copper, aluminum, and stainless steels are less susceptible to hydrogen embrittlement but still suffer from it.
The crack forms usually around the grain of the metallic compounds, as this is where the hydrogen atoms infiltrate and reduce ductility.
Source: MTC Solutions
This is a recurring problem for the development of a potential hydrogen economy, as traditional methods used for building pipelines, tanks, and valves face the very real issue of quick degradation and leaks forming.
This is a problem for building the infrastructure that mass deployment of hydrogen as a fuel will require.
Breakthrough Alloy: Scandium-Enhanced Aluminum
Adding Scandium
To reduce hydrogen embrittlement, the best solution is for other elements to absorb the hydrogen, protecting the aluminum metal from it. The researchers used a method creating aluminum-scandium (Al3Sc) nanoprecipitates.
Scandium is a rare earth element, whose only major application lies in aluminum alloys. Atom probe tomography (APT) showed that a normal aluminum-magnesium alloy has an average grain size of 200 μm. In contrast, the aluminum-magnesium-scandium alloy has an average grain size of only 100 μm.
Source: Nature
On these precipitates, a highly complex 3d structure of aluminum-magnesium-scandium (Al3(Mg,Sc)2) forms. It appears that the scandium stabilizes the structure and forms an outer shell of magnesium-scandium covering the aluminum grain in the alloy.
Source: Nature
These dual nanoprecipitates are distributed throughout the alloy to serve two key roles: the Al3(Mg,Sc)2 phase traps hydrogen and enhances resistance to hydrogen, while the fine Al3Sc particles boost strength.
Boosting Strength and Durability with Al₃(Mg,Sc)₂
The newly invented alloy has a 80% stronger yield strength (around 100 MPa), or the the maximum stress that can be applied before permanent shape change.
However, it also has 20% less total tensile elongation, or the length at which the alloy can be stretched before breaking, than scandium-free alloy.
In addition, the exposure to hydrogen is much less damaging, making even hydrogen-charged aluminum-magnesium-scandium alloy stronger than the hydrogen-free normal aluminum-magnesium alloy.
Source: Nature
Overall, this can be summarized as a 40% increase in strength and a five-fold improvement in hydrogen embrittlement resistance compared to scandium-free alloys.
“Our new design strategy solves this typical trade-off. We no longer have to choose between high strength and hydrogen resistance – this alloy delivers both.”
Pr. Baptiste Gault – Head of the group “atom probe tomography” at MPI-Susmat
Scientific Validation of Hydrogen Resistance
Later analysis with electron microscopy and computer modeling looked deeper into how it works.
The electron microscopy proved visually that the hydrogen atoms indeed accumulate in the same areas that are rich in scandium, proving the direct link between scandium and the protection of aluminum from hydrogen absorption and embrittlement.
Source: Nature
A computer model was also developed to theorize how the nanostructures form. It seems to indicate that the newly discovered alloy surpasses all known intermetallic compounds and crystal defects that have been experimentally reported or theoretically predicted in aluminum alloys until now.
Source: Nature
Scalable Solutions for Industrial Use
This method was also tested by researchers to work with various methods of producing aluminum alloy.
They also demonstrated scalability by using water-cooled copper mould casting and thermomechanical processing methods that align with current industrial standards.
This should become the basis for a future generation of aluminium materials tailored to the demands of a hydrogen-powered future: stronger, safer from embrittlement risks, and ready for deployment at industrial scale.
Investing in the Aluminum Industry
Alcoa: A Major Player in Aluminum Innovation
Alcoa Corporation (AA +1.88%)
Alcoa is a global aluminum company, with a presence all over the world, and over the entire aluminum supply chain, from bauxite ore to aluminum metal, as well as alumina (the intermediary product between bauxite and aluminum).
Source: Alcoa
The company 41.3 Mdmt (Million dry metric tons) bauxite operations in 2024 send 85% of its shipment to Alcoa refineries.
Only 32% of the 13.2 Mt of produced alumina is sent to Alcoa foundries, producing 2.6 million tons of aluminum in 2024, with the rest sold to third parties.
Source: Alcoa
The company produces aluminum in various forms to match the requirements of many different manufacturing industries.
Source: Alcoa
Overall, aluminum production is a very energy-intensive activity, consuming electricity directly for smelting, oil for mining, coal to provide carbon in the smelting process, as well as consuming energy-intensive materials like caustic chemicals.
Still, Alcoa has made major efforts to reduce its carbon footprint, making it an industry leader in terms of carbon emissions, in part thanks to hydroelectricity facilities. It also offers the Alcoa Sustana product line, with reduced carbon emissions and higher recycled metal content.
Source: Alcoa
Tariffs could impact the company, as facilities in Canada and Brazil (among others) are going to face steep tariffs to sell to the USA. However the company also has production facilities in the USA, and the value of domestically produced aluminum has risen accordingly, which should boost the profitability of Alcoa’s American foundries.
Source: Alcoa
Overall, Alcoa is a solid bet on the continuous popularity of aluminum for advanced manufacturing, aerospace, and power grid, all sectors where demand is expected to grow in the coming years.