TY - JOUR
T1 - Achieving ultrahigh strength in oxide-dispersion-strengthened CoCrNi alloy via in situ formation of coherent Y-Ti-O nanoprecipitates
AU - Mao, Wenhao
AU - Yang, Lu
AU - Jiang, Feilong
AU - He, Jiangping
AU - Luan, Junhua
AU - Jiao, Zengbao
AU - Ren, Fuzeng
N1 - Not related to any projects.
PY - 2023/8
Y1 - 2023/8
N2 - Oxide-dispersion-strengthened CoCrNi alloys were fabricated via in situ oxidation by adding Ti and Y, and non-in-situ oxidation by direct addition of Ti and Y2O3, referring to as Y-ODS and Y2O3-ODS alloys, respectively. Transmission electron microscopy (TEM) and atom probe tomography (APT) characterizations reveal that both alloys consist of an ultrafine-grained face-centered-cubic (fcc) matrix, a high number density of nanoscale Y-Ti-O precipitates and a small number of (Cr0.75Ti0.25)2O3 oxides. However, the nanoscale Y-Ti-O precipitates in the two alloys show distinct phase and microstructure. The Y2O3-ODS alloy contains only incoherent orthorhombic Y2TiO5 nanoprecipitates, but the Y-ODS alloy also contains a high density of fully coherent pyrochlore Y2Ti2O7 nanoprecipitates. The Y-ODS alloy achieves an ultrahigh yield strength of 1660 MPa, which is 320 MPa higher than that of the Y2O3-ODS one, but maintains the same ductility. Quantitative analysis of the strengthening mechanism indicates that such large difference in strength is mainly attributed to the presence of coherent Y2Ti2O7 nanoprecipitates in Y-ODS alloy. This study should provide significant insight into the design of ODS high/medium-entropy alloys via in situ oxidation during mechanical alloying and consolidation.
AB - Oxide-dispersion-strengthened CoCrNi alloys were fabricated via in situ oxidation by adding Ti and Y, and non-in-situ oxidation by direct addition of Ti and Y2O3, referring to as Y-ODS and Y2O3-ODS alloys, respectively. Transmission electron microscopy (TEM) and atom probe tomography (APT) characterizations reveal that both alloys consist of an ultrafine-grained face-centered-cubic (fcc) matrix, a high number density of nanoscale Y-Ti-O precipitates and a small number of (Cr0.75Ti0.25)2O3 oxides. However, the nanoscale Y-Ti-O precipitates in the two alloys show distinct phase and microstructure. The Y2O3-ODS alloy contains only incoherent orthorhombic Y2TiO5 nanoprecipitates, but the Y-ODS alloy also contains a high density of fully coherent pyrochlore Y2Ti2O7 nanoprecipitates. The Y-ODS alloy achieves an ultrahigh yield strength of 1660 MPa, which is 320 MPa higher than that of the Y2O3-ODS one, but maintains the same ductility. Quantitative analysis of the strengthening mechanism indicates that such large difference in strength is mainly attributed to the presence of coherent Y2Ti2O7 nanoprecipitates in Y-ODS alloy. This study should provide significant insight into the design of ODS high/medium-entropy alloys via in situ oxidation during mechanical alloying and consolidation.
KW - CoCrNi
KW - Coherent nanoprecipitates
KW - Medium-entropy alloy
KW - Oxide dispersion strengthening
UR - http://www.scopus.com/inward/record.url?scp=85166022105&partnerID=8YFLogxK
U2 - 10.1016/j.matdes.2023.112141
DO - 10.1016/j.matdes.2023.112141
M3 - Journal article
AN - SCOPUS:85166022105
SN - 0264-1275
VL - 232
JO - Materials and Design
JF - Materials and Design
M1 - 112141
ER -