North Carolina State University researchers have just uncovered a novel method of printing non-chrystaline metallic alloy constructs. In essence, this allows them to create large quantities of metallic glass. The technique employs the use of a laser-based powder bed technology acting on iron grains to create a thicker layer than conventional methods allow.
While researchers have produced types of metallic glass before, the key difference that 3D printing creates is one of quantity. The researchers believe that this method could allow for production in bulk. Another benefit to this finding is that it also presents opportunities to produce a whole plethora of different alloys. Ola Harrysson, corresponding author of the paper, states that “there is no reason this technique could not be used to produce any amorphous alloy“.
The production of metallic glass alloys provides many advantages to manufacturers in terms of material properties. Chief among them is a level of conductivity that can allow for better, more efficient electric motors. The alloys also have better wear-resistance, higher strength, and lighter weight structures.
Manufacturing Glass Alloys
One of the problems with producing glass alloys has always been that of cooling. Making metallic glass requires rapid cooling to prevent the crystalline structures from forming. Previously, this meant that scientists could only create smaller quantities of the metallic glass. The previous methods were limited in terms of their ‘alloy critical casting thickness’.
At the current rate the method lasers about 20 microns per layer. The machine lasers the powders on the build platform and then descends by 20 microns for the next layer. Due to the incremental way that the layers pile on top of each other, the cooling is not an issue.
“The idea of using additive manufacturing, or 3D printing, to produce metallic glass on scales larger than the critical casting thickness has been around for more than a decade,” lead researcher Zaynab Mahbooba says. “But this is the first published work demonstrating that we can actually do it. We were able to produce an amorphous iron alloy on a scale 15 times larger than its critical casting thickness.”
The researchers compiled their findings in the paper “Additive manufacturing of an iron-based bulk metallic glass larger than the critical casting thickness”. The abstract for the study is available here.