Pt1-xIrx films with x varying from 22.76 to 63.25 at. % are deposited on (100) Si wafer substrates at 400 degrees C by magnetron sputtering deposition. The effects of the Ir concentration on the microstructure, morphology, and hardness of PtIr films are investigated by field emission scanning electron microscopy, x-ray diffraction, atomic force microscopy, and nanoindentation system. The columnar structures are observed by field emission scanning electron microscopy. X-ray diffraction analysis reveals that PtIr films have preferred orientation along Pt(111) when the Ir concentration is below 50.84 at. %. When the Ir content is more than 50.84 at. %, the Pt Ir film shifts to another preferred orientation, Ir(111). The surface morphology is analyzed by atomic force microscopy. The roughness of the Pt Ir films decreases with increasing Ir content. The hardness of all the Pt Ir films is below 20 GPa. The maximum hardness of the Pt Ir films is about 14.9 GPa when the Ir concentration is 57.9 at. %. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3457490]