Grain Refinement of Phosphorus Deoxidised Copper

DHP-Cu has been modified with small additions of nanosized MgO particles, with and without P and B additions; and Mg, B, Ti and Al additions to investigate their effect on the grain structure under TP1 casting condition. In comparison to a reference DHP-Cu cast sample which exhibited mainly coarse columnar grains, a coarse equiaxed grain structure has been achieved with a single addition of nanosized MgO particles to a residual content of 34 ppm Mg. Whereas no grain refinement has been observed with nanosized MgO particles and P and B additions to a residual content of 109 ppm and 0.15% (nominal), respectively, and with a single addition of Mg to a residual content of 16 ppm. The combined additions of B and Ti, and B and Al to a nominal residual content slightly beyond the DHP-Cu specification have produced excessive coarsening of grains. Keywords: nanosized MgO particles; grain refinement; DHP-Cu