Harnessing Boron’s Properties for Metal Alloys

:: Wednesday, May 15, 2024 :: Posted By Maryam Moravej

Metal producers are facing increased demand to create stronger, more durable, and versatile metal alloys.

From enhancing structural integrity to improving performance in extreme conditions, boron-infused alloys offer a myriad of benefits that are reshaping industries and propelling technological advancements.

Boron is used to enhance three primary metallurgical materials: Aluminum, steel, and copper.

How is boron used in metals?

In metals, boron is added either in its elemental form or as part of boride compounds, such as titanium boride (TiB2), boron carbide (B4C), boron nitride (BN), or as ferroboron (FeB) for steel.

Boron is a multifunctional metallurgical additive used for:

  • High-performing fluxes that remove oxides and dissolve impurities
  • Slag stabilization, resulting in greater control over waste
  • Corrosion resistance and protection

Read more on borates in metallurgy

Reinforcing aluminum strength

Prized for its light weight, strength, and performance, aluminum is used across industries. Manufacturers want alloy producers to tailor aluminum’s properties to meet their unique specifications and performance requirements.

Boron, which is mainly used in alloys containing titanium (Al-Ti-B master alloy), can help improve the mechanical properties of aluminum by achieving finer grains and subsequently more grain boundaries.

An alloy with more grain boundaries has better strength, ductility, and toughness because the boundaries contribute to these properties through a mechanism called grain refinement strengthening defined by “Hall-Petch” law.

Not familiar with the Hall-Petch law? Imagine you're running on a track in a race. In this scenario, the Hall-Petch law is a rule that states the harder the track is, the slower you run. In aluminum, the "track" is actually the structure made up of tiny grains. The Hall-Petch law tells us that the smaller these grains are, the stronger the material becomes, but at the same time, it gets harder for the grains to slide past each other.

So, just like you run slower on a tougher track, in materials with smaller grains, it becomes harder for them to deform or break under stress, making the material stronger.

More corrosion resistant
When added to aluminum alloys, boron segregates to grain boundaries, which increases the alloy’s corrosion resistance by eliminating preferential precipitation.

Easier welding
Boron’s grain refinement capability makes it easier to weld aluminum alloys because a fine-grain structure is less prone to the formation of hot cracks during welding.

Controls impurities
Under certain conditions, elements such as vanadium and titanium form coarse precipitates that weaken aluminum alloys’ electrical and thermal conductivities. If boron is present, it can bind with these elements, prevent precipitation from taking place, and improve the electrical and thermal conductivity of the alloy.

Enhanced castability
Hot tearing and porosity are casting defects that boron helps mitigate by modifying the solidification process of aluminum alloys.

Precipitation hardening
In some aluminum alloys, boron facilitates the precipitation of discrete phases that strengthen the alloy through a mechanism known as “precipitation or age hardening.”

Better wear resistance
When boron is added to alloys in order to form borides, the alloy’s wear resistance improves considerably—increasing its lifespan.

Increasing steel hardenability

Even alloying steel with very low concentrations of boron (FeB) significantly increases steel’s hardenability. Boron is a cost-effective alternative for comparable, if not equal, levels of hardenability when compared to more expensive elements.

When steel is subject to thermal treatment (quenching), soft phase (austenite) could transform into a very strong phase (martensite). Adding a small amount of boron promotes this type of phase transformation and enables the creation of martensitic steel (MS) and Press-Hardened Steel (PHS).

Conventional uses of boron in steel include automotive components such as door frames, which are strengthened by boron-based alloys. You’ll also find steel alloys with boron in construction, heavy machinery, cutting tools, military applications, and even the nuclear industry.

Boron in copper alloys

Copper alloys employ boron on a less frequent basis than aluminum and steel. However, when used, boron offers:

  • Grain refinement
  • Deoxidation
  • Degassing (no porous casting appearance)
  • Improved electrical conductivity
  • Increased primary copper recovery during recycling process

Learn more about Rio Tinto copper

Many of our products form the basis for boride compounds. U.S. Borax is a part of Rio Tinto, which mines and manufactures aluminum, steel, and copper products. Our organization’s extensive expertise across materials means you’ll receive the proper support for your metallurgical application.

Learn more about how boron can enhance your metallurgical application



U.S. Borax, part of Rio Tinto, is a global leader in the supply and science of borates—naturally-occurring minerals containing boron and other elements. We are 1,000 people serving 650 customers with more than 1,800 delivery locations globally. We supply around 30% of the world’s need for refined borates from our world-class mine in Boron, California, about 100 miles northeast of Los Angeles.  Learn more about Rio Tinto.

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