microstructure of CuAg

CuAg forms a simple eutectic phase diagram. Hence various hardening mechanims can be adopted:

  • solid solution strengthening
  • grain boundary hardening
  • precipitation hardening
  • work hardening

 

Phase diagram of CuAg and precipitation modes (left) as well as microstructures of Cu7Ag (red) and Cu24Ag (blue)

 

 

Discontinuous precipitates are always connected to a boundary. In the case of CuAg alloys they start at high angle grain boundaries. Two routes are traced to suppress their formation: 1) Increase the eutectic phase to a level where the Cu matrix grains are not in contact anymore (this holds for Cu25Ag) and 2) modify the grain boundary by the addition of a insoluble element like Zr. This suppresses the diffusion along the grain boundary and hence enhances the formation of continuous precipitates.

Research on Cu-7Ag-0.05Zr alloys has been carried out for a couple of years. Here are the details:

 

  • formation of precipitates in CuAgZr
  • energetics of the precipitation reaction in CuAgZr
  • thermal treatments of CuAgZr alloys
  • TEM of CuAg alloys
  • fatigue of CuAg alloys
  • strength of CuAgZr alloys
  • magnetoresistance of CuAg alloys
  • first coil wound from CuAgZr