Synergistic effect of Nb and Zr additions on the structure-property relationships of nanocrystalline Cu processed by mechanical alloying and hot pressing

In the present study, bulk nanocrystallineCu(99.5)Zr(0.5), Cu99Nb1.0, and Cu(98.5)Zr(0.5)Nb(1.0)alloys have been synthesized by using mechanical alloying followed by hot pressing (HP) at 550 degrees C. Further, these asfabricated alloys were annealed at 800 degrees C and 900 degrees C for 1 h to investigate the structure-property correlation. Grain size and phase identification has been carried out using X-ray diffraction (XRD) and transmission electron microscopy (TEM). While mechanical properties were investigated using Vickers hardness and shear punch test (SPT). The grain size of the as-processed alloys was found to remain nanosized 41 +/- 2.2 nm in Cu99.5Zr0.5(CZ), 50 +/- 1.5 nm in Cu99Nb1.0(CN) and 26 +/- 1.2 nm in Cu98.5Zr0.5Nb1.0(CNZ) even after annealing at 900 degrees C. This is attributed to the stabilization of the nanosize grains by segregation of solute atoms (Nb and Zr) along grain boundaries and/or Zenner pinning by intermetallic precipitates like Cu5Zr in CZ and CNZ alloys. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

In this study, bulk nanocrystalline Cu-Zr-Nb alloys were synthesized and annealed to investigate the reasons for maintaining nanosized grains. The results showed that the grain size remained in the nanoscale range due to solute atoms segregation along grain boundaries and Zenner pinning by intermetallic precipitates.