Influence Of Grain Size On Α′ Cr Precipitation In An Isothermally Aged Fe-21Cr-5Al Alloy
Abstract
Cr-Rich Α′ Precipitation During Aging Typically Leads To Hardening And Accordingly Embrittlement Of FeCrAl Alloys, Which Needs To Be Suppressed. The Influence Of Grain Size On Α′ Precipitation Was Studied By Aging Coarse-Grained (CG), Ultra-Fine Grained (UFG), And Nanocrystalline (NC) Ferritic Kanthal-D [KD; Fe-21Cr-5Al (Wt.%) Alloy] At 450, 500 And 550 °C For 500 H. After Aging At 450 And 500 °C, Less Hardening Was Observed In The UFG KD Than In CG KD. Atom Probe Tomography Indicated A Lower Number Density And Larger Sized Intragranular Α′ In The UFG Versus The CG Alloy. The Smaller Grain Size And Higher Defect (Vacancy And Dislocation) Density In The UFG KD Facilitated Diffusion And Accordingly Enhanced Precipitation Kinetics, Leading To Coarsening Of Precipitates, As Well As Saturation Of Precipitation At Lower Temperatures, As Compared To Those In CG KD. No Hardening Occurred In UFG And CG KD After Aging At 550 °C, Indicating That The Miscibility Gap Is Between 500 And 550 °C. NC KD Exhibited Softening After Aging Owing To Grain Growth. Α′ Precipitation Occurred In NC KD Aged At 450 °C But Not At 500 °C, Indicating That Miscibility Gap Is Between 450 And 500 °C. Thus, The Significantly Smaller Grain Size In NC KD Decreased The Miscibility Gap, As Compared To That In CG And UFG KD. This Is Attributed To The Absorption Of Vacancies By Migrating Grain Boundaries During Aging, Suppressing Α′ Nucleation And Enhancing Cr Solubility.
Recommended Citation
M. Arivu and A. Hoffman and J. Poplawsky and I. Spinelli and C. Dai and R. B. Rebak and J. Cole and R. K. Islamgaliev and R. Z. Valiev and H. Wen, "Influence Of Grain Size On Α′ Cr Precipitation In An Isothermally Aged Fe-21Cr-5Al Alloy," Materialia, vol. 34, article no. 102047, Elsevier, May 2024.
The definitive version is available at https://doi.org/10.1016/j.mtla.2024.102047
Department(s)
Materials Science and Engineering
Keywords and Phrases
Atom probe tomography; Cr rich α′ precipitation; Grain boundaries; Iso-thermal Aging; Nano structured FeCrAl alloys; Sever plastic deformation
International Standard Serial Number (ISSN)
2589-1529
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2024 Elsevier, All rights reserved.
Publication Date
01 May 2024
Comments
Russian Science Foundation, Grant 22-23-00714