Electron-beam evaporated nickel was deposited onto sapphire or rocksalt substrates at room temperature with and without simultaneous argon ion bombardment. The ion energies were 100, 500, or 1500 eV, with ion-to-atom arrival ratios, R, ranging from 0.01 to 0.1. For each film, the microstructure, density, resistivity, and amount of retained argon was measured. It was determined that 100 eV bombardment produced an increase in density with little change in resistivity, whereas 1500 eV bombardment decreased the density and increased the resistivity monotonically with R. The reduction in density was correlated with decreasing microstructural feature size and decreased preferred orientation which suggested that the ions induced an increase in the volume fraction of boundaries.