Abstract
Yttrium oxide dispersion strengthened (ODS) and non-ODS EUROFER produced by mechanical alloying and hot isostatic pressing have been subjected to isochronal annealing up to 1523K, and the evolution of the open-volume defects and their thermal stability have been investigated using positron lifetime and coincidence Doppler broadening (CDB) techniques. Transmission electron microscopy (TEM) observations have also been performed on the studied samples to verify the characteristics of the surviving defects after annealing at 1523K. The CDB spectra of ODS EUROFER exhibit a characteristic signature that is attributed to positron annihilation in Ar-decorated cavities at the oxide particle/matrix interfaces. The variation of the positron annihilation parameters with the annealing temperature shows three stages: up to 623K, between 823 and 1323K, and above 1323K. Three-dimensional vacancy clusters, or voids, are detected in either materials in as-HIPed condition and after annealing at T⩽623K. In the temperature range 823–1323K, these voids’ growth and nucleation and the growth of other new species of voids take place. Above 1323K, some unstable cavities start to anneal out, and cavities associated to oxide particles and other small precipitates survive to annealing at 1523K. The TEM observations and the positron annihilation results indicate that these cavities should be decorated with Ar atoms absorbed during the mechanical alloying process.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.