Shape Memory and Superelasticity

, Volume 4, Issue 4, pp 402–410 | Cite as

Designing NiTiAg Shape Memory Alloys by Vacuum Arc Remelting: First Practical Insights on Melting and Casting

  • Gilberto H. T. Álvares da Silva
  • Jorge Otubo


NiTi-based shape memory alloys are successful owing to its capacity to cover specific applications unreachable by binary NiTi. The additions of ternary, and even quaternary, elements are intended to change specific properties. Known for its antibacterial activity, Ag became an alloying element in a search for a functional biomaterial; however, the melting appears to hampering the system exploration. A special melting procedure by vacuum arc remelting was developed based on chemical and thermal analysis, via EDS, XRF, and DSC, assessing the element loss and ingot homogeneity, respectively. By alloy design, different Ag content NiTiAg SMA were produced and analyzed on as-cast condition. The melting procedure developed involves specific feedstock cares and preparation, melting, and some remelting steps. The measured chemical composition slightly differs from the nominal due to alloying element loss and the melting reaction thermodynamics. Being the lower the possible, the remelting steps were optimized to maintain the compromise between chemical composition and compositional homogeneity through the ingot, since the Ag content stabilizes along them, also indicating a limited content possible to be alloyed. Ag-yields are content-dependent, while the Ni:Ti relation is stable, being therefore the melting of NiTiAg SMA better performed by VAR than other melting routes under high vacuum conditions.


NiTiAg Alloy design Melting Biocompatibility 



This research was supported by the Grant 2012/15302-0, São Paulo Research Foundation (FAPESP). The authors are also thankful to the Aeronautics Institute of Technology for the laboratory facilities.


  1. 1.
    Buehler WJ, Gilfrich JV, Wiley RC (1963) Effect of low-temperature phase changes in mechanical properties of alloys near composition of TiNi. J Appl Phys 34:1475–1477CrossRefGoogle Scholar
  2. 2.
    Otsuka K, Ren X (2005) Physical metallurgy of Ti–Ni-based shape memory alloys. Prog Mater Sci 50:511–678CrossRefGoogle Scholar
  3. 3.
    Rondelli G (1996) Corrosion resistance tests on NiTi shape memory alloy. Biomaterials 17:2003–2008CrossRefGoogle Scholar
  4. 4.
    McMahon RE, Ma J, Verkhoturov SV, Munoz-Pinto D, Karaman I, Rubitschek F, Maier HJ, Hahn MS (2012) A comparative study of the cytotoxicity and corrosion resistance of nickel-titanium and titanium-niobium shape memory alloys. Acta Biomater 8:2863–2870CrossRefGoogle Scholar
  5. 5.
    Es-Souni M, Es-Souni M, Fischer-Brandies H (2002) On the properties of two binary NiTi shape memory alloys. Effects of surface finish on the corrosion behavior and in vitro biocompatibility. Biomaterials 23:2887–2894CrossRefGoogle Scholar
  6. 6.
    Ryhänen J, Niemi E, Serlo W, Neimelä E, Sandvik P, Pernu H, Salo T (1997) Biocompatibility of nickel-titanium shape memory metal and its corrosion behavior in human cell cultures. J Biomed Mater Res A 35:451–457CrossRefGoogle Scholar
  7. 7.
    Dutta RS, Mandagopal K, Gadiyar HS, Banerjee S (1993) Biocompatibility of NiTi shape memory alloy. Br Corros J 28:217–221CrossRefGoogle Scholar
  8. 8.
    Haider W, Munroe N, Pulletikurthi C, Singh Gill PK, Amruthaluri S (2009) Comparative biocompatibility analysis of ternary Nitinol alloys. J Mater Eng Perform 18:760–764CrossRefGoogle Scholar
  9. 9.
    Otubo J, Rigo OD, Moura Neto C, Mei PR (2006) The effects of vacum induction melting and electron beam melting techniques on the purity of NiTi shape memory alloys. Mater Sci Eng A 438–440:679–682CrossRefGoogle Scholar
  10. 10.
    Forooozmehr A, Kermanpur A, Ashrafizadeh F, Kabiri Y (2011) Investigation microstructural evolution during homogenization of the equiatomic NiTi shape memory alloy produced by vacuum arc remelting. Mater Sci Eng A 528:7952–7955CrossRefGoogle Scholar
  11. 11.
    Kabiri Y, Kermanpur A, Forooozmehr A (2012) Comparative study on microstructure and homogeneity of NiTi shape memory alloy produced by copper boat induction melting and conventional vacuum arc remelting. Vacuum 86:1073–1077CrossRefGoogle Scholar
  12. 12.
    Otubo J, Rigo OD, Moura Neto C, Mei PR (2003) Scale up NiTi shape memory alloy produced by EBM. J Phys IV 112:873–876Google Scholar
  13. 13.
    Tuissi A, Rondelli G, Bassani P (2015) Plasma arc melting (PAM) and corrosion resistance of pure NiTi shape memory alloys. Shap Mem Superelasticity 1:50–57CrossRefGoogle Scholar
  14. 14.
    Zhang B, Chen J, Coddet C (2013) Microstructure transformation behavior on in situ shape memory alloys by selective laser melting Ti–Ni mixed powder. J Mater Sci Technol 29(9):863–867CrossRefGoogle Scholar
  15. 15.
    Eckelmeyer KH (1976) The effect of alloying on the shape memory phenomenon in Nitinol. Scr Metall Mater 10:667–672CrossRefGoogle Scholar
  16. 16.
    Zhao YN, Jiang SY, Zhang YQ, Liang YL (2017) Influence of Fe addition on phase transformation, microstructure and mechanical properties of equiatomic NiTi shape memory alloy. Acta Metall Sin 30:762–770CrossRefGoogle Scholar
  17. 17.
    Melton KN, Mercier O (1980) The mechanical properties of NiTi-based shape memory alloys. Acta Metall Mater 29:393–398CrossRefGoogle Scholar
  18. 18.
    Ma J, Karaman I, Noebe RD (2013) High temperature shape memory alloys. Int Mater Rev 55:257–315CrossRefGoogle Scholar
  19. 19.
    Miyazaki S, Ishida A (1999) Martensitic transformation and shape memory behavior in sputter-deposit TiNi-based thin films. Mater Sci Eng A 273–275:106–133CrossRefGoogle Scholar
  20. 20.
    Tosetti JPV, da Silva GHTA, Otubo J (2014) Microstructure evolution during fabrication of Ni–Ti–Nb SMA wires. Mater Sci Forum 775–776:534–537CrossRefGoogle Scholar
  21. 21.
    Matsumoto H (1991) Addition on an element to NiTi alloy by an electron-beam melting mehod. J Mater Sci Lett 10:417–419CrossRefGoogle Scholar
  22. 22.
    Oh KT, Joo UH, Park GH, Hwang CJ, Kim KM (2006) Effect of silver addition on the properties on nickel-titanium alloys for dental applications. J Biomed Mater Res 76:306–314CrossRefGoogle Scholar
  23. 23.
    Zheng YF, Zhang BB, Wang BL, Wang YB, Li L, Yang QB, Cui LS (2011) Introduction of antibacterial function into biomedical TiNi shape memory alloy by the addition of element Ag. Acta Biomater 7:2758–2767CrossRefGoogle Scholar
  24. 24.
    Frenzel J, George EP, Dlouhy A, Somsen CH, Wagner MF-X, Eggler G (2010) Influence of Ni on the martensitic phase transformations in NiTi shape memory alloys. Acta Metall Mater 58:3444–3458CrossRefGoogle Scholar
  25. 25.
    Sadrnezhaad SK, Badakhshan Raz S (2005) Ingredient losses during melting binay Ni–Ti shape memory alloys. J Mater Sci Technol 21:484–488Google Scholar
  26. 26.
    da Silva GHTA (2015) Elaboração e caracterização de ligas ternárias NiTiAg com efeito memória de forma, DsC Thesis, Available from Aeronautics Institute of Technology Library, BRA. Thesis completed December, 2015Google Scholar
  27. 27.
    Duerig TW, Bhattacharya K (2015) The influence of the R-phase on the superelastic behavior of NiTi. Shap Mem Superelasticity 1:153–161CrossRefGoogle Scholar
  28. 28.
    Sitepu H (2003) Use of synchrotron diffraction data for describing crystal structure and crystallographic phase analysis of R-phase NiTi shape memory alloy. Texture Microstruct 35(3/4):185–195CrossRefGoogle Scholar

Copyright information

© ASM International 2018

Authors and Affiliations

  1. 1.Department of Metallurgical and Materials EngineeringFederal University of Ouro PretoOuro PretoBrazil
  2. 2.ITASMART Group, Department of MaterialsAeronautics Institute of TechnologySão José dos CamposBrazil

Personalised recommendations