The morphology and atomic structures of Ni-stabilized ''1 X 1'' domains formed on rapid-quenched Si(lll) surfaces were studied using atomic force microscopy (AFM) in air and scanning tunneling microscopy (STM) in a vacuum. Quantitative analysis of the surface morphologies by ex situ AFM showed that the widths for inhibiting the 1 X 1 stabilization near monoatomic steps depended on Ni deposition of between 1.8 X 10(-2) and 9 x 10(-4) monolayers (ML). For Ni depositions of less than 9 X 10(-4) ML, the protrusion of the 1 X 1 domain decreased. In situ STM study revealed that the 7 X 7 reconstruction had nucleated in the 1 X 1 domains.