High-strength aluminium alloys still fight the powder bed

The alloys that make aluminium worth using in structures are the ones that crack during solidification. Getting past that has meant designing new alloys rather than new parameters.

By LasersNews Desk·22 Jul 2026·2 min read

Detailed view of a high-tech 3D printer mechanism showcasing precision engineering. — Photo by FOX ^.ᆽ.^= ∫ on Pexels

Aluminium is attractive for additive manufacturing wherever mass matters. Yet the alloys actually printed in volume are casting alloys — AlSi10Mg and similar — while the high-strength 2000 and 7000 series alloys that dominate aerospace structures have resisted the process for years.

The solidification cracking mechanism

Powder bed fusion solidifies a small melt pool very quickly under strong thermal gradients. High-strength aluminium alloys have wide freezing ranges, meaning a substantial temperature interval where solid and liquid coexist.

In that mushy zone, solidifying grains form a network while liquid remains between them. Contraction pulls the network apart, and if liquid cannot flow to fill the gap, a crack forms. Rapid solidification plus high thermal stress makes those conditions almost unavoidable.

Casting alloys near eutectic composition solidify over a narrow range and largely avoid the problem, which is why they print well and why the printable aluminium palette was so limited.

The nucleation approach

The development that changed this came from materials rather than process. Adding nucleating particles — zirconium-based compounds have received the most attention — promotes fine equiaxed grains rather than long columnar ones.

A fine equiaxed structure accommodates contraction strain in many small increments distributed across many grain boundaries, rather than concentrating it. Liquid also feeds more readily through the finer network. Alloys that cracked reliably become printable.

Where it stands

Several modified high-strength aluminium alloys are now commercially available, with properties approaching wrought equivalents after heat treatment. Adoption is progressing in aerospace brackets and structural components where the geometry justifies additive.

The remaining constraints are familiar: powder cost, qualification burden, and the fact that a printed part must beat a machined billet on total cost, which for simple geometries it rarely does.

The broader pattern

This is the clearest example in metal AM of a limitation solved by changing the material rather than the machine. Alloy development for additive processes — as opposed to adapting alloys designed for casting or wrought processing — is now an established field, and aluminium was the application that made the case for it.

This article was produced by the LasersNews AI desk and reviewed by our editors.