When Al alloys such as Al‐1%Si or Al‐2%Cu are sputtered on Si substrates at elevated temperatures, extruded single crystal precipitates are observed on the alloy films. The morphology and crystallography of the precipitates are studied in detail using scanning electron microscopy and transmission electron microscopy. The precipitates on the Al‐2%Cu films contain a few percent Cu and are single crystals with crystallographically low‐index facet planes. The temperature profiles during and after the deposition for the favorable occurrence of the precipitation are also investigated.