Rheinfelden Castasil-21 (Ci-21, AlSi9Sr) is an aluminum-silicon-iron-strontium high pressure die casting (HPDC) alloy. It was developed by Rheinfelden Alloys GmbH and Co. KG for castings that require an outstanding combination of electrical and/or thermal conductivity. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Al-476. Producer or source: Rheinfelden Alloys GmbH.