Engineering news
A study published today in the journal Nature Communications has found that high-frequency sound waves can have a big impact on the inner structure of 3D-printed alloys – making them stronger and more consistent than those made with traditional additive manufacturing.
"If you look at the microscopic structure of 3D-printed alloys, they're often made up of large and elongated crystals," says Carmelo Todaro, lead author of the study, and a PhD candidate at RMIT University’s School of Engineering in Melbourne, Australia. “This can make them less acceptable for engineering applications due to their lower mechanical performance and increased tendency to crack during printing.”
Applying ultrasound changed that, and the alloys made using the process looked markedly different. “The alloy crystals were very fine and fully equiaxed, meaning they had formed equally in all directions throughout the entire printed metal part,” Todaro says.
The team tried the ultrasound approach with two major commercial-grade alloys: Ti-6Al-4V, a titanium alloy commonly used for aircraft parts and implants; and Inconel 625, a nickel-based superalloy used in the marine and petroleum industries.
Testing revealed that the parts had a 12 per cent improvement in tensile strength and yield stress compared with those made with conventional additive manufacturing.
By switching the ultrasound generator on and off during printing, the team were also able to show how different parts of a 3D-printed structure could be made with different microscopic structures and compositions.
"Although we used a titanium alloy and a nickel-based superalloy, we expect that the method can be applicable to other commercial metals, such as stainless steels, aluminium alloys and cobalt alloys," says Ma Quin, co-author of the study and a distinguished professor at RMIT. "We anticipate this technique can be scaled up to enable 3D printing of most industrially relevant metal alloys for higher-performance structural parts or structurally graded alloys."