Processing and functional stability of Ti-Ta-based high temperature shape memory alloysTuesday (15.05.2018) 13:30 - 13:55 Part of:
Ti-Ta shape memory alloys (SMAs) are attractive for applications as high temperature SMAs due to their high MS temperatures and excellent workability. We provide results on processing and functional stability of Ti-Ta SMAs. We show how high quality Ti-Ta alloys can be produced through arc melting and subsequent thermal and thermomechanical treatments. A processing route involving rotary swaging, wire drawing and thermal treatments was developed. Although the workability of Ti-Ta is relatively good, the production of thin wires is not trivial. Most importantly, the oxidation-related formation of brittle alpha-Ti layers in surface regions promotes the formation of a high density of cracks. Therefore, thermal exposure during processing needs to be minimized. We present a processing route which yields wires with defined microstructures and good surface conditions. We also provide results on cyclic functional testing of Ti-Ta spring actuators which were prepared from wire materials with different compositions.