Effects of zirconium addition on the material properties and microstructure of ODS-Cu alloys

Abstract

An oxide dispersion strengthened copper (ODS-Cu) alloy with Zr addition was fabricated by high-energy water-cooled mechanical alloying and spark plasma sintering (SPS). The effects of Zr addition on the material properties and microstructure of ODS-Cu alloys were investigated by comparing with the results of the Cu-1Y2O3 (wt%) ODS alloy. The addition of 0.81 Zr (wt%) to the Cu-1Y2O3 (wt%) alloy was confirmed to increase the Vickers hardness of the ODS-Cu alloy by a factor of 1.5, resulting in an unprecedented value of 243 HV. The excellent strength comes mainly from the strengthening effect caused by the refinement of the dispersed oxide particles. Fine and dense FCC-structured complex Y2Zr2O7 oxide particles were found to be uniformly distributed within the alloy, which are in good coherency with the Cu matrix, allowing the particle size to be less than half of that in Cu-1Y2O3 (wt%) ODS alloy at 7.6 nm. Although a slight decrease in the thermal diffusivity of the ODS-Cu alloy with Zr was observed, which can be attributed to the solid solution effect of the residual Fe in the matrix, this study proposes a suitable thermal aging treatment to restore the thermal diffusivity by precipitating the solute Fe.