Effect of process parameters on the microstructure and properties of TiC dispersion strengthened copper alloys

Copper alloys with high electrical and thermal conductivities in combination with high elevated temperature strength can be developed, if finest thermodynamically stable TiC dispersoids are included into a copper matrix. For manufacturing TiC dispersion strengthened copper alloys, mechanical alloying was carried out in a planetary ball mill using a blend of atomized prealloyed CuTi(X) powder and graphite powder. Information on the mechanism of forming TiC dispersoids during milling and heating at various temperatures was obtained by using X-ray diffraction and TEM investigations. Another way of manufacturing TiC dispersion strengthened copper alloys was to mill preformed, finely dispersed TiC powder (50 nm) into pure copper powder. The two various processing techniques used made it possible to produce TiC dispersoids with different interface to the copper matrix. In addition, it was possible to change the microcrystalline microstructure of the dispersion strengthened alloys (100-300 nm) into a coarse-grained microstructure (200-500 mu m) by heat treatment. The microstructure of these alloys is demonstrated by TEM and HRTEM investigations. The room temperature properties and the high temperature creep behavior of the alloys are described according to the different interfaces of the TiC dispersoids to the copper matrix, the position and the size of the TiC dispersoids and the grain size of the matrix.