Cr cluster characterization in Cu-Cr-Zr alloy after ECAP processing and aging using SANS and HAADF-STEM

Abstract

The precipitation of nano-sized Cr clusters was investigated in a commercial Cu-1Cr-0.1Zr (wt.%) alloy processed by equal-channel angular pressing and subsequent aging at 550 • C for 4 h using Small-Angle Neutron Scattering (SANS) measurements and High-Angle Annular Dark-Field-Scanning Transmission Electron Microscopy (HAADF-STEM). The size and volume fraction of the nano-sized Cr clusters were estimated using both techniques. The parameter values assessed by SANS (d ∼ 3.2 nm, Fv ∼ 1.1 %) agreed reasonably with those by HAADF-STEM (d ∼ 2.5 nm, Fv ∼ 2.3 %). In addition to the nano-sized Cr clusters, HAADF-STEM indicated the presence of rare cuboid and spheroid sub-micronic Cr particles measuring approximately 380-620 nm in mean size. Both techniques did not evidence the presence of intermetallic CuxZry phases within the aging conditions.