Metal Injection Moulding of Superelastic TiNi Parts

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 Ti₄Ni₂O_x 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.

• Periodical: Key Engineering Materials (Volume 704)
• Pages: 173-182
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.704.173
• Online since: August 2016
• Authors: J. Eric Bidaux*, Alexandra Amherd Hidalgo, Hervé Girard, Mikel Rodriguez-Arbaizar, Lionel Reynard, Jacques Chevallier, François Aeby, Jean Charles Giachetto, Efrain Carreño-Morelli
• Keywords: Dental Applications, Metal Injection Moulding, Superelasticity, Titanium-Nickel Alloys

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