Effect of Heat Treatment on Microstructure of Continuous Unidirectional Solidified Cu-Ni-Sn Alloy

Cu-15%Ni-8%Sn alloy was prepared by continuous unidirectional solidification (CUS) processing and the as-cast CUS Cu-15%Ni-8%Sn alloywas homogenized. The evolution of microstructure and composition distribution of as-cast and annealed CUS Cu-15%Ni-8%Sn alloy was analyzed. The results show that the microstructure of as-cast CUS Cu-15%Ni-8%Sn is mainly composed of coarse columnar grains and there exist segregation phenomenon in the grain boundaries. After annealing at temperature of 850 degrees C for 30 min, it was found that the composition of the alloy began to become uniform and the solutes gathered at the grain boundaries diffused into the columnar grains.