Phase separation in a two-dimensional Co-Cr alloy

Two-dimensional phase separation in a Co-Cr random binary alloy on a W(110) surface was confirmed with ultra-high-vacuum scanning tunneling microscopy . With 1.1 ML Co and 0.1 ML Cr co-deposited at room temperature, the film s hows a kinetically limited structure. Upon annealing, phase separation betw een Co and Cr-rich phases of similar to 100 Angstrom size was observed. Evi dence of compositional inhomogeneity was observed in Cr-rich phases but not in Co-rich phases. (C) 1999 American Institute of Physics. [S0003-6951(99) 04008-5].