Abstract
We have assessed the structural evolution and dispersoid coarsening behaviors of the oxide dispersion-strengthened superalloy MA754 during two different melt-based additive manufacturing techniques – metal laser powder bed fusion (PBF-LB/M) and directed energy deposition (DED). The mechanically alloyed MA754 powder posed challenges for both processes due to its irregular flaky morphology and large particle size. Successful consolidation with PBF-LB/M required increasing the layer height, decreasing the scanning speed, and increasing the laser power relative to typical Ni superalloy printing parameters. The resulting materials contained residual porosity and large Y-Al-oxide slag inclusions which formed in situ. The more prolonged thermal excursion during DED resulted in even larger, mm-scale slag inclusions, which spanned several build layers. In both PBF-LB/M and DED, these inclusions grew at the expense of nanoscale dispersoids, depleting the material of this strengthening phase. These observations motivate alternative approaches for preparing dispersion-strengthened powder feedstocks besides mechanical alloying and highlight the deleterious effects of Al microalloying on dispersoid stability and structure.
| Original language | English |
|---|---|
| Article number | 100195 |
| Journal | Additive Manufacturing Letters |
| Volume | 9 |
| DOIs | |
| State | Published - Apr 2024 |
Funding
The authors from MIT gratefully acknowledge support from ONR through contract no. N00014-22-1-2036. This research used equipment funded by Australian Research Council grants LE0882821 and LE110100223. A portion of this research used resources at the High Flux Isotope Reactor, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. The authors acknowledge the use of instruments and scientific and technical assistance of Dr. Emily Chen, Dr. Timothy Williams, and Dr. Yang Liu at the Monash Centre for Electron Microscopy (MCEM), Monash University, the Victorian Node of Microscopy Australia. The authors would like to thank Dr. Tom Jarvis, Mr. John Shurvinton and Mr. Bryce Melville for their assistance with DED fabrication, and Dr. Kun Zhang, Mr. Chun Kit Sit and Mr. Shengbin Dai for their help with characterization. The authors from MIT gratefully acknowledge support from ONR through contract no. N00014-22-1-2036 . This research used equipment funded by Australian Research Council grants LE0882821 and LE110100223 . A portion of this research used resources at the High Flux Isotope Reactor, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. The authors acknowledge the use of instruments and scientific and technical assistance of Dr. Emily Chen, Dr. Timothy Williams, and Dr. Yang Liu at the Monash Centre for Electron Microscopy (MCEM), Monash University, the Victorian Node of Microscopy Australia. The authors would like to thank Dr. Tom Jarvis, Mr. John Shurvinton and Mr. Bryce Melville for their assistance with DED fabrication, and Dr. Kun Zhang, Mr. Chun Kit Sit and Mr. Shengbin Dai for their help with characterization.
Keywords
- Additive manufacturing
- Coarsening
- Nickel superalloys
- Oxide dispersion strengthening
