In Year 1 (July 1, 2002 to September 30, 2003) of this project, NiTiFe powders were arc-melted. The NiTiFe buttons were subsequently thermomechanically processed in order to successfully demonstrate shape-memory and actuator properties. A range of compositions were fabricated and tested. In Year 2 (October 1, 2003 to September 30, 2004), the alloys developed were incorporated in a prototype cryogenic thermal conduction switch and successfully tested. In order to investigate deformation in these materials in situ, during loading at cryogenic temperatures, for the first time a facility for cryogenic loading during neutron diffraction was developed at Los Alamos National Laboratory. The goals in Year 3 (October 1, 2004 to September 30, 2005) are to (i) improve on the aforementioned prototype as outlined in this proposal (ii) to test the fabricated alloys at Los Alamos National Laboratory at cryogenic temperatures (iii) to continue using dilatometry, indentation and calorimetry at UCF to optimize these alloys, while additionally measuring stresses and strains during actuation and (iv) to scale-up alloy production quantities by recourse to hot isostatic processing (HIP).

Shape-memory alloys when deformed can produce strains as high as 8%. Heating results in a phase transformation and associated recovery of all the accumulated strain, a phenomenon known as shape-memory. This strain recovery can occur against large forces, resulting in their use as actuators. The goal of this project is to lower the operating temperature range of shape-memory alloys in order for them to be used in cryogenic switches, seals, valves, fluid-line repair and self-healing gaskets for hydrogen related technologies. This is primarily accomplished by: 1. Alloy development: The Ni-Ti-Fe alloy system, previously used in Grumman F-14 aircrafts and activated at 120 K, is further developed through arc-melting a range of compositions and subsequent thermomechanical processing. 2. Materials testing and evaluation: A combination of indentation, diffraction, calorimetry and dilatometry techniques are employed to optimize the fabricated alloys. Particularly, a unique in situ cryogenic loading capability during neutron diffraction, developed in partnership with Sierra Lobo at NASA KSC, is used to investigate these alloys at Los Alamos National Laboratory. 3. Cryogenic actuator design and prototype construction: Designs of cryogenic actuators are analyzed and implemented. Initial emphasis is placed on developing a cryogenic thermal conduction switch for NASA KSC and this is followed by focusing on seals and valves.