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Synthesis of Super-porous Nano Structure Nitinol by Milling using Space Holder Technics and Measure of Termomechanical Properties

Khalatbari, Mohammad Saleh | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 44686 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Sadrnezhad, Khatiboleslam
  7. Abstract:
  8. NiTi is known as a most important material for manufacturing implants and other medical devises duo to its shape memory and super elasticity properties, high energy damping and high corrosion resistance.In this project the possibility of producing nano structured NiTi implant with high porosity was investigated. For reaching to nano scale mechanical alloying process was done on Ti and Ni powder as row materials. Mechanical alloying process and the possibility of reaching nano structure or amorphous phase was investigated. Space holder technic was used for reaching a porous structure. Sintering process was planned in a way to inhibit grain growth as much as possible. The samples sintered in two different temperatures. The effect of grain size and secondary phases on mechanical properties and phase transformation temperatures was studied. It is shown that the presence of secondary phases will lead to decreasing transformation temperatures. Grain size has the same effect. In fact one of the effect of reaching to nano sacales is decreasing transformation temperatures due to high dislocation density and high grain boundaries surface. Nano structured sample by 70% porosity was shown a 5% superelasticity in cyclic pressure test. Actually one of the advantages of porous samples are their elastic modulus which are more similar to bone than other metallic implants
  9. Keywords:
  10. Porosity ; Nanostructure ; Nitinol Alloy ; Superelasticity ; Nickel-Titanium Shape Memory Alloy

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