Microstructure and mechanical property of Y2O3-based ODS-Cu alloy fabricated by MA-HIP with novel elemental addition process

Abstract

The oxide dispersion strengthened (ODS)-Cu alloys produced by the combined process of mechanical alloying and hot isothermal pressing (MA-HIP) process have high strength properties, although they have low ductility. In this study, the MA-HIP process was modified based on the yttrium addition and oxygen addition methods to improve the ductility by controlling the microstructure of the ODS-Cu alloys. Namely, we replaced pure Y and Cu2O powders with a Cu-Y intermetallic compound and pre-heated Cu powders as the starting materials. The final product showed considerable microstructural differences: on the macro-scale, the frequency of interconnection of large/small Cu grain colonies, which was a main factor in brittle fracture, was reduced; while on the nanoscale, yttrium remained as yttria (Y2O3) particles within the large size Cu grains. These multiscale microstructural changes resulted in the improved mechanical property: the newly-developed ODS-Cu bulk did not fracture at bending strains of 18% or greater, which can be compared with the previous value of 5% or less in a three-point bending test. Furthermore, the conductivities of our ODS-Cu alloys are 94–96% of pure Cu. This improvement in properties, therefore sheds light to the future application of the ODS-Cu alloys in high-temperature environments.