Extraction of precipitates from age-hardenable Cu-Ti alloys

An extraction procedure has been developed to separate the precipitates, namely, metastable fine α-Cu4Ti with a tetragonal structure and stable coarse β-Cu4Ti with an orthorhombic structure, from an age-hardenable Cu-Ti alloys. When the alloy was submerged in a 7.0 M nitric acid solution at 273 K, only the Cu solid solution matrix was dissolved chemically, and both precipitates were left as insoluble residue. Subsequent structural and chemical-compositional analyses of the insoluble residue and filtrate determined the mass fraction and composition of the precipitates and matrix with high accuracy.