Abstract
Oxide dispersion strengthened CoCrFeMnNi high-entropy alloys (ODS-HEAs) were prepared using two different powder preparation methods classified by yttrium addition strategy to investigate the effects of in-situ and ex-situ oxide dispersoid formation on the microstructure and mechanical properties. Systematic microstructural analysis was carried out by X-ray diffraction (XRD), electron backscattered diffraction (EBSD), high-resolution transmission electron microscopy (HRTEM), atom probe tomography (APT), and small-angle neutron scattering (SANS). Cryo-milled powder analysis, grain structure evolution after spark plasma sintering, dispersoid characteristics, and matrix/dispersoid interface structure analysis of the in-situ and ex-situ dispersoids within the high-entropy alloy (HEA) matrix were performed. The in-situ dispersoid formation was dominantly observed in the Y-alloyed ODS-HEA through the construction of a coherent interface relationship with complex chemical composition, leading to an increase in the Zener pinning forces on the grain boundary movement. ODS-HEA with in-situ oxide dispersoids enhanced the formation of ultrafine-grained structures with an average diameter of 330 nm at a sintering temperature of 1173 K. This study shows that the Y pre-alloying method is efficient in achieving fine coherent dispersoids with an ultrafine-grained structure, resulting in an enhancement of the tensile strength of the CoCrFeMnNi HEA.
| Original language | English |
|---|---|
| Pages (from-to) | 62-75 |
| Number of pages | 14 |
| Journal | Journal of Materials Science and Technology |
| Volume | 85 |
| DOIs | |
| State | Published - Sep 20 2021 |
Funding
The authors thank Mr. Taesung Park (EBSD) of Center for Research Facilities Hanbat National University, XRD and TEM group of KAIST Analysis Center for Research Advancement (KARA), Dr. Bong Ho Lee (APT) of DGIST Center for Core Research Facilities and Dr. Changwoo Do (SANS) of ORNL for their technical discussions. SANS was carried out at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. This study was supported by the Civil-Military Technology Cooperation Program under the Agency for Defence Development (ADD) of the Republic of Korea(No. 1415156504), the National Research Foundation grant funded by the Korean government (Nos. NRF-2020R1A5A6017701 and 2017K1A3A7A09016308) The authors thank Mr. Taesung Park (EBSD) of Center for Research Facilities Hanbat National University, XRD and TEM group of KAIST Analysis Center for Research Advancement (KARA), Dr. Bong Ho Lee (APT) of DGIST Center for Core Research Facilities and Dr. Changwoo Do (SANS) of ORNL for their technical discussions. SANS was carried out at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. This study was supported by the Civil-Military Technology Cooperation Program under the Agency for Defence Development (ADD) of the Republic of Korea (No. 1415156504 ), the National Research Foundation grant funded by the Korean government (Nos. NRF-2020R1A5A6017701 and 2017K1A3A7A09016308 )
| Funders | Funder number |
|---|---|
| Center for Research Facilities Hanbat National University | |
| Civil-Military Technology Cooperation Program | |
| Office of Science | |
| Oak Ridge National Laboratory | |
| National Research Foundation of Korea | 2017K1A3A7A09016308, NRF-2020R1A5A6017701 |
| Agency for Defense Development | 1415156504 |
Keywords
- High-entropy alloy
- In-situ oxide dispersoid formation
- Mechanical property
- Microstructure
- Oxide dispersion strengthened (ODS) alloy