PRECIPITATION EFFECTS DURING HOT DEFORMATION OF A COPPER ALLOY

Hot compression tests were performed on a previously solution-treated Cu-3Ni-1Si-O.8Cr-O.1Mg alloy below the solvus temperature. The effects of precipitation occurring during hot deformation and the accompanying flow stresses were analyzed on the basis of microstructural evolution using optical, scanning, and transmission electron microscopy, and microhardness measurements. It was found that the hardening stage was followed by strain-induced localized Ni2Si-precipitate coarsening at the temperature related to the most effective dynamic precipitation. Intensive coarsening of precipitates began at grain boundaries. Very fine Ni2Si precipitates were transformed into elongated particles at grain boundaries, producing flow localization, softening, and finally sample fracture.