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Development of a new near-net shape method to produce NiTi

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NiTi alloys are used in actuators and medical devices because of their unique shape-memory properties. More widespread application of NiTi is still limited by their poor machinability and high processing cost.

Injection moulding would provide near-net shape manufacturing, minimising the need for machining. So far only few investigations of NiTi powder injection moulding have been performed. Those using elemental powders for feedstock are even more limited. This last route is however interesting from an economic point of view since it avoids the delicate production of the pre-alloyed powder.

The purpose of the present project was to examine the feasibility of manufacturing NiTi by powder injection moulding using elemental powder for feedstock. For the first time, titanium hydride (TiH2) powder was used for the fabrication of NiTi parts by injection moulding. The presence of a reversible martensitic transformation above room temperature was revealed by differential scanning calorimetry. Shape memory effects of more than 4% have been measured.

Shape memory effects measured in injection moulded NiTi