A Comparison of Atomic Mixing Behaviour of Cu - Au and Cu - W Systems for Room Temperature and Low Temperature Irradiation

Abstract

300 keV Kr ion irradiations with doses varying from 2 × 10¹⁵ to 2 × 10¹⁶ at/cm have been applied to initiate mixing of Cu-Au and Cu-W systems. As under normal thermodynamic conditions the Cu-Au system is miscible whereas the Cu-W system is not, the comparison of both systems provides a test for the current theories on ion-beam mixing. A pronounced difference in mixing phenomena is observed for both systems; in the Cu-Au system atomic displacements are one order of magnitude larger than those in the Cu-W system. In addition, a drastic temperature dependence of ion-beam mixing in the Cu-Au system has been found. The mixing is suppressed by lowering the substrate temperature during irradiation. These results show that radiation enhanced diffusion is the mechanism underlying the ion-beam mixing of Cu and Au. Results for the Cu-W system are consistent with a collisional mixing model.