Fatigue and Fracture Behavior of Porous TiNi Alloys

Abstract:

While the wide range of applications of TiNi alloys make them highly appealing due to their shape memory and superelasticity properties, production of TiNi in the porous form further enlarges their application fields. Porous TiNi alloys have been studied extensively for biomedical applications due to their elastic modulus similar to that of bone. Accordingly, TiNi 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 the scope of this study, fatigue behavior of TiNi foams, which were produced from prealloyed powders by Mg space holder technique, was examined via load controlled cyclic compression-compression tests. The endurance limit of the tested foams was taken as the stress level at which the specimens sustain their integrity without showing any sign of failure beyond 10⁶ cycles. TiNi foams with porosity contents in the range of 39-64 vol%, which is suitable for bone ingrowth, were determined to have an endurance limit ranging in between 26-89 MPa. On the other hand, fractography studies on the failed foams after fatigue testing revealed that the failure occurs by the coalescence of micro-cracks initiated from pore walls leading to macro-crack formation aligned at 45^o with respect to the loading axis.

• Periodical: Materials Science Forum (Volumes 783-786)
• Pages: 591-596
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.783-786.591
• Online since: May 2014
• Authors: G. Ipek Nakaş*, Emin Erkan Aşık, Bensu Tunca, Şakir Bor
• Keywords: Biomedical Applications, Fatigue, Powder metallurgy, Space Holder Technique, Titanium Alloy

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