Fabrication of biomedical cancellous NiTi by starch consolidation of pre-alloyed powder
Examensarbete för masterexamen
Shape memory alloys are alloys that through phase change and/or deformation have the properties of superelasticity and shape memory effect (SME). The first implies no temperature change and occurs upon stress release. The second implies recovering very large shape changes through heating. NiTi is a shape memory alloy of equiatomic configuration. Proven biocompatibility and above mentioned properties with their similarity to corresponding properties of bone makes it an alternative very comparable to already established implant materials such as stainless steel and titanium. Due to the relatively high melting temperature of NiTi, powder metallurgy is a key fabrication technology, where passing or reaching melting temperature is avoided. Today bulk NiTi is made for e.g. guide-wires and pipe seals. However, fabricating NiTi in a porous form expands the application area with e.g. filter inserts and cancellous bone replacements. With the use of powder metallurgy this can be achieved. One fabrication method is starch consolidation followed by solid state sintering. It implies using starch as both binder and pore former. With pre-alloyed NiTi powder, this method and loose powder sintering are evaluated by mechanical tests and analysis of microstructure in this thesis. The results show that it is possible to generate porous NiTi structures for further development of desired superelastic behaviour.
Metallurgi och metalliska material , Materialvetenskap , Produktion , Metallurgy and Metallic Materials , Materials Science , Production