Aug 15, 2017 | By Benedict

Researchers at Carnegie Mellon University have designed a rapid screening method for new 3D printing alloys. The method allows users to quickly understand and develop correlations between process variables and alloy composition.

(l-r) Titanium boron (Ti-B) alloy before and after it is refined by an additive manufacturing laser pass. Courtesy Carnegie Mellon University College of Engineering

Creating new metal powders for additive manufacturing can be a slow and laborious process. Because despite the countless number of metals and alloys out there, relatively few of these materials possess the right physical properties for being turned into powder and then sintered, melted, or jetted.

Designing a new alloy for 3D printing, for example, takes a lot of time. Lots of powder—sometimes hundreds of pounds worth—is needed to carry out the requisite tests, and this is no guarantee that the end product will even be printable.

“Even at a research scale, it’s not straightforward or efficient to fabricate small batches of powder for every possible material composition that we need to test,” explained Bryan Webler, assistant professor of materials science and engineering at Carnegie Mellon. “We need computational and experimental approaches to screen compositions to provide some initial guidance before we try to make test batches of powders.”

Faced with this problem, Webler and his team have devised a new rapid screening method that provides the kind of “guidance” needed to develop alloys for 3D printing. They say the method could save engineers lots of time and money in the long run.

Somewhat counterintuitively, the researchers’ method involves the use of solid materials instead of powders. Using an arc-melting process, the team can produce small metal buttons from the powder being tested. Up to 16 of these buttons can be placed on the bed of a metal 3D printer, which can make “tracks and pads of remelted material” on each button over a range of process variables.

This process allows the researchers to adjust certain variables—beam power, travel speed, etc.—on each metal button to see the results. Characterizing the resulting melt pools allows the team to gain insights into how that alloy reacts to the fast solidification rates of 3D printing.

Alloy button with process variable test tracks. Courtesy Carnegie Mellon University College of Engineering.

“This screening method allows us to...more quickly understand and develop correlations between process variables and alloy composition,” Webler said.

Carnegie Mellon University, a private research university in Pittsburgh, Pennsylvania, is turning into something of a hotbed for additive powder research. In June, it was revealed how engineers at the university were using machine vision technology to sort metal 3D printing powders with 95 percent accuracy.

With Webler’s team developing a method for identifying suitable 3D printing alloys and Elizabeth Holm’s team finding a way to screen powder batches for anomalies, Carnegie Mellon can boast of a suite of new and invaluable additive manufacturing processes.

 

 

Posted in 3D Printing Materials

 

Source: Carnegie Mellon University

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