Microstructure Evolution of Cu-15Ni-8Sn Alloy Prepared by Vertical Semi-continuous Casting with EMS

In the present study, vertical semi-continuous casting equipped with the electromagnetic stirring (EMS) was applied in order to control the solidification process and obtain the anticipated homogeneous microstructure for Cu-15Ni-8Sn alloy. The experimental results indicate that the microstructure of as-cast Cu-15Ni-8Sn (wt.%) alloy prepared by conventional casting consists of Sn-depleted alpha phase (alpha Cu(Ni) solid solution), Sn-rich gamma phase ((CuxNi1-x)(3)Sn), and intermediate transition region (alpha+gamma), and most of the Sn element mainly segregates at dendritic grain boundary. Discriminatively, some equiaxed grains come into being in as-cast Cu-15Ni-8Sn alloy prepared by vertical semi-continuous casting, and Sn-rich gamma phases distribute on the matrix and grain boundary uniformly. Furthermore, the size of equiaxed grains becomes smaller after applying EMS, which reduces the segregation of Sn element to a large degree. In this study, microstructure evolution mechanism of Cu-15Ni-8Sn alloy prepared by conventional casting and by vertical semi-continuous casting without and with EMS is analyzed.