Spinodal decomposition in a melt-spun Cu-15Ni-8Sn alloy

We investigate the spinodal decomposition process in a melt-spun Cu-15Ni-8Sn alloy using X-ray diffraction (XRD), transmission electron microscopy (TEM), and electron diffraction analyses. In the XRD measurements, an aging treatment of more than 300 min at 350 °C was required to obtain the (200) sidebands. TEM observations of the melt-spun samples aged at 350 °C for 40, 60, and 300 min showed a modulated structure with a wavelength too small to be detected by TEM and aging for about 1200 min was required for the clear appearance of a modulated structure. The electron diffraction patterns showed only the disordered fcc phase with no satellite structures in the sample aged for 20 min at 350 °C, which implied that no spinodal decomposition occurred. Aging for 40 min at 350 °C was required before the super-lattice reflection of DO22 was observed. These experimental results indicate that the decomposition process in the melt-spun alloy was slow initially.