The Processing and Fatigue Characterization of TiNi and Ti-6Al-4V Porous Materials

Abstract:

Porous titanium alloys have been extensively studied in biomedical applications due to their elastic moduli similar to that of bone compared to other implant materials. Accordingly, TiNi and Ti-6Al-4V foams have been widely characterized in terms of their various mechanical properties; however, their fatigue properties have not been well studied, even though, it has a vital importance in structural applications such as medical implants. In this study, porous titanium alloys were processed via sintering at 1200 °C for 2 hours employing Mg space holder technique. TiNi and Ti-6Al-4V alloys with a porosity of 49 and 51 vol.%, respectively, were mechanically characterized by monotonic and cyclic compression tests. The compressive strength was determined to be 148 MPa for TiNi foams whereas 172 MPa for Ti-6Al-4V foams with homogenously distributed pores having diameters in the range of 250-600 µm. Endurance limit values were determined relative to the yield strength of each porous alloy in order to enable the comparison of fatigue behavior. The fatigue tests applied with a frequency of 5 Hz and a constant stress ratio (σ_min/σ_max) of 0.1 have revealed that porous TiNi alloys have an endurance limit of approximately 0.6 σ_y whereas porous Ti-6Al-4V alloys have an endurance limit of approximately 0.75 σ_y. The differences and similarities in the microstructure and their effect on mechanical behavior of the two alloys were also studied by employing scanning electron microscope (SEM).

• Periodical: Key Engineering Materials (Volumes 493-494)
• Pages: 930-935
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.493-494.930
• Online since: October 2011
• Authors: Emin Erkan Aşık, Gül Ipek Nakaş, Şakir Bor
• Keywords: Biomedical Applications, Fatigue, Space-Holder Technique, Ti6Al4V, TiNi

References

[1] M. Geetha, A.K. Singh, R. Asokamani, A.K. Gogia, Ti based biomaterials, the ultimate choice for orthopaedic implants – A review, Prog. Mater. Sci. 54 (2009) 397–425.

DOI: 10.1016/j.pmatsci.2008.06.004

[2] H.J. Rack, J.I. Qazi, Titanium alloys for biomedical applications, Mat. Sci. Eng. C 26 (2006) 1269 – 1277.

[3] K. Kuribayashi, K. Tsuchiya, Z. You, D. Tomusb, M. Umemotob, T. Ito, M. Sasaki, Self-deployable origami stent grafts as a biomedical application of Ni-rich TiNi shape memory alloy foil, Mat. Sci. Eng. A 419 (2006) 131–137.

DOI: 10.1016/j.msea.2005.12.016

[4] K. Otsuka, X. Ren, Recent developments in the research of shape memory alloys, Intermetallics 7 (1999) 511-528.

DOI: 10.1016/s0966-9795(98)00070-3

[5] A. Bansiddhi, T.D. Sargeant, S.I. Stupp, D.C. Dunand, Porous NiTi for bone implants: A review, Acta Biomater. 4 (2008) 773–782.

DOI: 10.1016/j.actbio.2008.02.009

[6] H. Li, B. Yuan, Y. Gao, C.Y. Chung, M. Zhu, High-porosity NiTi superelastic alloys fabricated by low-pressure sintering using titanium hydride as pore-forming agent, J. Mater. Sci. 44 (2009) 875–881.

DOI: 10.1007/s10853-008-3193-x

[7] E. Schüller, M. Bram, H.P. Buchkremer, D. Stöver, Phase transformation temperatures for NiTi alloys prepared by powder metallurgical processes, Mat. Sci. Eng. A 378 (2004) 165–169.

DOI: 10.1016/j.msea.2003.10.341

[8] T. Aydoğmuş, Ş. Bor, Processing of porous TiNi alloys using magnesium as space holder, J. Alcom. 478 (2009) 705-710.

DOI: 10.1016/j.jallcom.2008.11.141

[9] G. Ryan, A. Pandit, D.P. Apatsidis, Fabrication methods of porous metals for use in orthopaedic applications, Biomaterials 27 (2006) 2651–2670.

DOI: 10.1016/j.biomaterials.2005.12.002

[10] S.A. Shabalovskaya, Surface, corrosion and biocompatibility aspects of Nitinol as an implant material, Bio-Med. Mater. Eng. 12 (2002) 69–109.

[11] S. Kujalaa, J. Ryhanena, A. Danilovb, J. Tuukkanen, Effect of porosity on the osteointegration and bone ingrowth of a weight-bearing nickel–titanium bone graft substitute, Biomaterials 24 (2003) 4691–4697.

DOI: 10.1016/s0142-9612(03)00359-4

[12] P.H. Pennekamp, J. Gessmann, O. Diedrich, B. Burian, M.A. Wimmer, V.M. Frauchiger, C.N. Kraft, Short-Term Microvascular Response of Striated Muscle to cp-Ti, Ti-6Al-4V, and Ti-6Al-7Nb, J. Orthop. Res. 24 (2006) 531-540.

DOI: 10.1002/jor.20066

[13] J.P. Li, P. Habibovic, M. van den Doel, C.E. Wilson, J.R. de Wijn, C.A. van Blitterswijk, K. de Groot, Bone ingrowth in porous titanium implants produced by 3D fiber deposition, Biomaterials 28 (2007) 2810–2820.

DOI: 10.1016/j.biomaterials.2007.02.020

[14] C. Greiner, S.M. Oppenheimer, D.C. Dunand, High strength, low stiffness, porous NiTi with superelastic properties, Acta Biomater. 1 (2005) 705–716.

DOI: 10.1016/j.actbio.2005.07.005

[15] X. Huang, Y. Liu, Effect of annealing on transformation behavior and superelasticity of NiTi shape memory alloys, Scripta Mater. 45 (2001) 153-160.

DOI: 10.1016/s1359-6462(01)01005-3

[16] X. Li, C. Wang, W. Zhang and Y. Li, Fabrication and compressive properties of Ti6Al4V implant with honeycomb-like structure for biomedical applications, Rapid Prototyping J. 16 (2010) 44–49.

DOI: 10.1108/13552541011011703

[17] Z. Esen, Ş. Bor, Processing of titanium foams using magnesium spacer particles, Scripta Mater. 56 (2007) 341–344.

DOI: 10.1016/j.scriptamat.2006.11.010

[18] G.İ. Nakaş, A.F. Dericioğlu, Ş. Bor, Fatigue behavior of TiNi foams processed by magnesium space holder technique, J. Mech. Behav. Biomed. (2011) In Press.

DOI: 10.1016/j.msea.2013.06.011