Microstructure and properties of a Cu-Ni-Cr spinodal alloy

A commercial Cu-28 pct Ni-2.8 pct Cr alloy has been heat treated to produce spinodal structures. Conventional transmission electron microscopy (TEM) and diffraction have been used to study the spinodally decomposed product and to measure the wavelengths in the specimens. It is found that the coarsening of coherent particles obeys the relation λαt ^1/3 at 700δC and λ αt ^1/4 at 600°C. Loss of coherency is observed only when aging at 700°C and λ ~ 1000?, when interfacial dislocations with b = a/2 (110) are created after which the coarsening rate is accelerated. Tensile tests were performed to measure mechanical properties of the aged samples, and the fracture surfaces were examined by scanning electron microscopy. The correlations of microstructural changes and mechanical properties are discussed.