Study Of Deformation-Processed Cu-10%Cr-3%Ag In Situ Composites

The Cu-10%Cr-3%Ag in situ composites that was melted in a vacuum induction furnace and machined by drawing at room temperature combined with intermediate heat treatments. The as-cast alloy and the deformed in situ composites' microstructure, strength, electrical conductivity, and the relationship between them were studied. It was found from SEM conversation that Cr phase transferred from the dendrites in as-cast status to the shape of tadpole paralleling drawing direction which deformation started from one set of the dendrites. At last, they all become into fibers. And the fibers were curl and fold. The heavier the deformation is, the more and firmer the fibers are. It was found from strength and electrical conductivity test that with the increases of the deformation, the composites was greatly strengthened by some kinds of strengthening methods in which the interface strengthen and work hardening play the most important roles. The Ultimate Tensile Strength of the sample at η=2.92 was 485MPa and that of sample at η=6.2 was 955MPa. The resistivity was slightly increased during the deformation processes because of the increase of interface scattering. On the other hand, during the intermediate heat treatments, the solute atoms scattering resistivity was sharply decrease because the Cr atoms precipitate, so the resistivity of deformed composite is lower than that of the cast alloy.Almost all of the Ag atoms in deformation Cu-10%Cr-3%Ag in situ composite dissolve in Cu based matrix. Some Ag atoms exist in the interface of Cu/Cu or Cr/Cu.The intermediate heat treatments with different temperature (420°C-550°C)have different effects on the mechanical property and electrical conductivity;Test results show that as increase of intermediate heat temperature from 420°Cto 550°C, the conductivity decrease first and then increase, and the strengthincrease first and then decrease.The sample with intermediate heat temperature at 485°C has the best result.Some good combination of mechanical property and electrical risistivity of...