We have studied the atomic mixing of Sb layers in Al induced by irradiation with 110 keV Ar ions. Samples with 10 and 230 Å Sb layers sandwiched in Al were made by sequential vacuum deposition and analyzed by backscattering spectrometry. The mixing was characterized by finding the increase, σ2, in the variance of the Sb signal in the backscattering spectra. For 10 Å layers irradiated at 90 and 270 K, the profiles are Gaussian and σ2 increases linearly with dose of implanted Ar ions. The mixing is essentially independent of temperature up to ∼ 290 K, where it increases sharply. For 230 Å layers irradiated at 90 and 270 K, the profiles are approximately Gaussian but develop a flat top as the Al:Sb ratio approaches 1:1. At 90 K σ2 increases monotonically with dose up to 3.6 × 1016 Ar/cm2, but at 270 K it develops a plateau at a dose of ∼ 2.2 × 1016 Ar/cm2, which corresponds to Al:Sb = 1:1. No such plateau is observed at 90 K. Again, the mixing showed very little variation with temperature between 90 and 270 K, but rose abruptly above 300 K.