Metal injection moulding of superelastic TiNi parts

Contact   Bidaux Jacques-Eric
Title   Metal injection moulding of superelastic TiNi parts
Author(s)   Bidaux J.-E., Amherd Hidalgo A., Girard H., Rodriguez-Arbaizar M., Reynard L., Chevallier J., Aeby F., Giachetto J.-C., Carreño-Morelli E.
References   Key Engineering Materials, 2016, vol. 704, pp. 173-182
Abstract   TiNi shape-memory properties are successfully used today for the fabrication of various technical devices. The limited machinability and high cost of TiNi encourage the use of near-net shape production techniques such as metal injection moulding. In this work TiNi alloys tensile test specimens are produced by metal injection moulding from pre-alloyed powders. A binder based on a mixture of polyethylene, paraffin wax and stearic acid is used. Parts with a density of about 96.6% of theoretical density are obtained. Scanning electron microscopy coupled with EDX measurements reveals a microstructure consisting of a TiNi matrix with small Ti4Ni2Ox and TiC inclusions. DSC and X-ray diffraction observations indicate the presence of additional Ni4Ti3 precipitates. The parts exhibit full superelasticity at room temperature even for strains of up to 4%, without the need for additional thermal post-treatments. Ultimate tensile strengths up to 980 MPa are obtained.
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