Session: 16-04-03: AM Bench Plenaries III

Paper Number: 172842

Benchmarking Phase Transformations in Fe-Cr-Ni Alloys During Laser Melting: Insights From Amb2025-08 

Additive manufacturing (AM) processes often involve extreme thermal gradients and rapid solidification rates, resulting in microstructures that differ significantly from those produced by conventional processing methods. A key scientific and technological challenge is to understand and predict phase transformations under these far-from-equilibrium conditions. Challenge Problem AMB2025-08, part of the AM-Bench 2025 initiative sponsored by the National Institute of Standards and Technology (NIST), aims to benchmark the modeling community’s ability to accurately simulate phase evolution in Fe-Cr-Ni alloys subjected to laser melting.

This benchmark consists of two components: (1) Phase Transformation Sequence (PTS) and (2) Phase Transformation Kinetics (PTK). The PTS challenge asks modelers to identify the order in which phases form during solidification and subsequent cooling, including any metastable or transient phases prior to reaching equilibrium. The PTK challenge requires a time-resolved prediction of phase fraction evolution, with a focus on solid-state transformation mechanisms such as diffusion-driven reactions.

To support this benchmark, high-speed, high-energy synchrotron X-ray diffraction experiments were conducted at the Advanced Photon Source (APS) at Argonne National Laboratory. Fe-Cr-Ni alloy samples were fabricated using vacuum arc melting, followed by homogenization, cold rolling, and recrystallization annealing to ensure uniform composition and refined, equiaxed grain structures suitable for diffraction analysis. Final specimens were polished to a mirror finish and machined with precision to ensure consistent laser-material interaction.

During the experiments, a 520 W ytterbium fiber laser was used to generate single linear melt tracks. In situ X-ray diffraction data were acquired at 250 Hz using a Pilatus3 CdTe area detector, capturing the complete solidification and phase transformation sequence from the melt to room temperature.

This presentation will highlight the scientific motivation behind the benchmark, as well as the experimental setup, specimen preparation, and data acquisition strategies. Results from four different Fe-Cr-Ni alloys processed under varying laser conditions will be presented, illustrating how composition and processing parameters influence phase evolution. We will also summarize the modeling results submitted for both challenges, providing insight into the current capabilities of the simulation community in accurately and precisely predicting phase transformations in AM.

The high-quality, reproducible data generated through this benchmark will be made publicly available via MIADS, NIST’s materials data portal. This dataset will serve as a foundation for the quantitative validation of simulation tools, supporting the advancement of predictive modeling in materials design and advanced manufacturing. Ultimately, this work addresses one of the grand challenges in materials physics: understanding and modeling materials behavior far from equilibrium.

Presenting Author: Fan Zhang National Institute of Standards and Technology

Presenting Author Biography: Dr. Fan Zhang is a senior physicist in the Materials Measurement Science Division of the Material Measurement Laboratory at the National Institute of Standards and Technology (NIST). He leads the NIST project titled "Structural Metrology of Advanced Manufacturing Processes." His research focuses on developing and utilizing advanced characterization tools, particularly those available at high-energy synchrotron sources, to investigate complex phase transformation behaviors in advanced materials. Dr. Zhang has served on many scientific committees, including as chair of the Advanced Photon Source Users Organization. He currently serves as chair of the Advanced Characterization, Testing, and Simulation Committee of The Minerals, Metals & Materials Society (TMS).

Authors:

Fan Zhang National Institute of Standards and Technology
Joseph Aroh National Institute of Standards and Technology
Andrew Chuang Argonne National Laboratory