I am a third-year PhD student in the Mechanical and Aerospace Engineering Department. My research focuses on using gas atomization to produce metal powders in Dr. Horn’s research group at CAMAL. These metal powders are then used as feedstock for metal additive manufacturing (AM) technologies. Using this pilot-scale system, I have produced a wide variety of metal powders, including steels, nickel-based superalloys, copper alloys, and refractory alloys. I characterize both the powders and the resulting AM parts at the AIF using XRF, XRD, and SEM with EDS and EBSD.

What instruments are you using for your research and why do you like them?

The first step in powder analysis is validating the chemistry because the melting process during atomization can change the alloy composition. I use X-ray fluorescence (XRF) to compare the chemistry of the atomization feedstock with that of the atomized powders.

I use the Rigaku Supermini200 to perform XRF analysis. I also use the Rigaku parallel-beam diffractometer to evaluate powder samples using X-ray diffraction (XRD) and determine which phases are present in the powders’ final state.

Gas atomization produces spherical powders, and obtaining the ideal morphology is critical. I use scanning electron microscopy (SEM), specifically the Hitachi SU3900VP SEM, to examine loose powders mounted on carbon tape. To examine particle cross sections in greater detail, I mount and polish the powders before examining them with the Hitachi SU8700 microscope. I also use energy-dispersive spectroscopy (EDS) on both microscopes to observe the chemical distribution on and within the powder particles.

After the atomized powders have been used in AM processes, such as laser or electron beam powder bed fusion, I repeat these analyses. I use XRF to determine whether the chemistry changed during remelting in the AM process, XRD to determine whether the phases present changed because of thermal processing, and SEM to examine the microstructure of the AM parts. Finally, I use electron backscatter diffraction (EBSD) on the SU8700 microscope to quantify the grain structure.

What have you been researching?

I am studying the differences in material properties between alloys produced through AM and those produced through traditional processing methods. AM parts can have anisotropic properties, and the exact processing conditions can be difficult to control. This makes it challenging to qualify AM parts for critical-service applications.

Specifically, I am studying a group of alloys that are approved by ASME for use in boiler and pressure-vessel components. In my work, I produce powders for different alloys within this group that are not commercially available and study their properties after they are processed using laser powder bed fusion (LPBF) and electron beam powder bed fusion (EBPBF).

Qualifying these alloys for AM production could enable dramatic increases in energy-production efficiency by improving heat extraction in nuclear and traditional power plants. The increased efficiency of AM heat exchangers could also reduce the size of these components, helping make systems such as small modular reactors more practical.

“Qualifying these alloys for AM production could enable dramatic increases in energy-production efficiency.”
– Ben Labiner

What have you learned from your experience at AIF?

Working with the AIF has been a constant learning experience. The staff members are all incredibly knowledgeable in their respective fields and are always open to discussing everything from experimental design to the niche physics behind different pieces of equipment. Learning how to operate the instruments is important, but the AIF stands out because of its ability to teach students why the instruments work.

Best thing about AIF in five words or fewer?

Everything about the AIF rocks!

Is there a staff member at AIF who has helped you?

Every staff member at the AIF has been incredibly helpful, but I am especially appreciative of Jenny Forrester and Toby Tung. Jenny trained me on all the X-ray equipment I use and has always made herself available to discuss results and experimental plans. Toby trained me on the SEMs I use and is always willing to help with the practical work involved in imaging a sample.