In the present study, bulk nanocrystallineCu99.5Zr0.5, Cu99Nb1.0, and Cu98.5Zr0.5Nb1.0alloys have been synthesized by using mechanical alloying followed by hot pressing (HP) at 550 °C. Further, these as-fabricated alloys were annealed at 800 °C and 900 °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 °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.