MECHANICAL-PROPERTIES AND SHAPE-MEMORY OF POROUS NITINOL

The mechanical properties and shape memory effect parameters of new porous TiNi alloys for implantation and prothesis were reviewed. Their porous structure provides excellent ingrowth in living tissue and firm fixation. Due to their generally good biocompatibility, these materials can serve in the body for a long time without being removed. Two manufacturing methods of porous TiNi are described here, powder sintering and ignition synthesis. Porous TiNi alloys manufactured using these methods exhibit superelasticity and shape memory effect, the parameters of which strongly depend on the conditions of sintering or synthesis. Under certain conditions, these parameters approach those of solid alloys. The yield strength, the percent of shape recovery, and the stored recoverable strain are controlled by porosity. Higher porosity and low average magnitude of plastic deformation result in a higher percent of shape recovery and recoverable strains.