RMIT scientists have demonstrated a new ‘ultrasound’ approach for 3D printing metal alloys that are more consistent and stronger than those printed conventionally.
The scientists led by Distinguished Professor Ma Qian, used sound vibrations to shake metal alloy grains into tighter formation during 3D printing.
According to lead author and PhD candidate Carmelo Todaro, the results of this study could inspire new forms of additive manufacturing:
“If you look at the microscopic structure of 3D printed alloys, they’re often made up of large and elongated crystals.”
“This can make them less acceptable for engineering applications due to their lower mechanical performance and increased tendency to crack during printing.”
“But the microscopic structure of the alloys we applied ultrasound to during printing 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.”
Upon testing these parts, the scientists found that they had a 12% improvement in tensile strength and yield stress compared to those made through conventional additive manufacturing.
The new ultrasound approach was demonstrated using two major commercial grade alloys:
The first was a titanium alloy commonly used for aircraft parts and biomechanical implants, known as Ti-6Al-4V.
The second was a nickel-based superalloy often used in marine and petroleum industries called Inconel 625.
By simply switching the ultrasonic generator on and off during printing, the team also showed how specific parts of a 3D printed object can be made with different microscopic structures and compositions, useful for what’s known as functional grading.
Professor Qian adds that this method can also be applied to other commercial metals, such as stainless steels, aluminium alloys and cobalt alloys:
“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.”
Image and content: RMIT