Co-base ODS alloys, strengthened by nanosized oxide dispersion and γ′ precipitates, were prepared by mechanical alloying. Hot compression tests were performed in the temperature range of 25-970 °C with the strain rate varying from 0.0001 to 0.01 s-1. The influence of deformation parameters and Y2O3 content on the flow behavior and the microstructure of compressive specimens were investigated. It was observed that Co-base ODS alloys had exhibited the homogeneous distribution of ultrafine γ′ precipitates (0.26 μm), nanosized oxide particle (12.5 nm), and small grains (1.1 μm). The enhanced flow stress at low temperatures and high strain rates was attributed to the rapid multiplication of dislocations due to the pining effect of oxide dispersion, γ′ precipitates, and fine grains. The peak stress had decreased with increasing the deformation temperature as well as by decreasing the strain rate. The obvious improvement in flow stress was acquired by increasing the Y2O 3 contents. Grain boundary sliding and porosity growth had been considered to be the main softening mechanisms during the hot deformation at elevated temperature. Moreover, It was found that the flow softening could be accelerated by decreasing the strain rate. The activation energy had increased with increasing temperature, but decreased with decreasing strain rate.
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