Effects of P addition on spinodal decomposition and discontinuous precipitation in Cu-15Ni-8Sn alloy

The microstructure and subsequent phase transformations of Cu-15Ni-8Sn can get affected by a minor addition of phosphorus (P). For the first time, the hexagonal Ni10SnP3 phase was observed in the Cu-15M-8Sn-0.2P alloy using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and transmission electron microscope (TEM). Further, the atomic size factor increased which was responsible for the promotion of the spinodal decomposition and ordering in Cu-15Ni-8Sn alloy with P addition. Moreover, the Ni10SnP3 phase precipitated along the grain boundary, and the precipitation free-zone was observed near the grain boundary. Nonetheless, these were the primary causes observed for the inhibition of discontinuous precipitation (DP) with P addition.