Metallurgy Breakthrough: Engineers 3D Print 'Unweldable' High-Strength Aluminum
Researchers from HRL Laboratories have developed a technique for 3D printing high-strength unweldable aluminum alloys, including types Al7075 and Al6061 - a breakthrough that opens the door to additive manufacturing of engineering-relevant alloys. These alloys are very desirable for aircraft and automobile parts and have been among thousands that were not previously amenable to 3D printing. Additive manufacturing of metals typically begins with alloy powders that are applied in thin layers and heated with a laser or other direct heat source to melt and solidify the layers. Normally, if high-strength unweldable aluminum alloys such as Al7075 or AL6061 are used, the resulting parts suffer severe hot cracking. HRL's nanoparticle functionalization technique solves this problem by decorating the alloy powders with specially selected nanoparticles. The nanoparticle-functionalized powder is fed into a 3D printer, which layers the powder and laser-fuses each layer to construct a three-dimensional object. During melting and solidification, the nanoparticles act as nucleation sites for the desired alloy microstructure, preventing hot cracking and allowing for retention of full alloy strength in the manufactured part.