Refined microstructure and enhanced mechanical properties in Mo-Y2O3 alloys prepared by freeze-drying method and subsequent low temperature sintering

The ultrafine Mo-Y2O3 composite powders were successfully synthesized by innovative freeze-drying method. Consequently, the freeze-dried Mo-Y2O3 composite powders with high sintering activities possess an average grain size of 54 nm. After low temperature sintering at 1600 degrees C, the Mo-Y2O3 alloys maintaining a high density (99.6 %) have the finest grain size (620 nm) comparing with available literature about oxide dispersion strengthened molybdenum alloy (ODS-Mo). The oxide particles remain their small size (mainly <50 nm) within Mo grains and at Mo grain boundaries. Furthermore, the Y5Mo2O12 particles were firstly observed within Mo matrix, and its formation can absorb nearby oxygen impurities, which involves the purification of Mo matrix. The mechanical properties show that Mo-Y2O3 alloy possess a high hardness of 487 +/- 28 HV0.2, a high yield strength of 902 MPa, a high compressive strength of 1110 MPa, respectively. Our work suggests that freeze-drying and subsequent low temperature sintering can shed light on the preparation of ultrafine ODS-Mo alloys with high performance. (C) 2021 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

The ultrafine Mo-Y2O3 composite powders were synthesized successfully by innovative freeze-drying method, showing high sintering activities and fine grain size. The resulting Mo-Y2O3 alloys have high density, fine grain size, and excellent mechanical properties, suggesting the potential for high-performance ultrafine ODS-Mo alloys preparation using freeze-drying and low temperature sintering.