Document Type : Original Research Article


1 Department of Material Science and Engineering Sharif University of Technology Tehran, Iran

2 Biotechnology Department, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran


Objective(s): NiTi is known as the most important material for manufacturing implants and medical devises duo to its shape memory and superelasticity properties, high energy damping, and high corrosion resistance.
Methods: In this project, the possibility of producing nanostructured NiTi implant with high porosity was investigated. For reaching to the nanoscale, the mechanical alloying process was done on Ti and Ni powder as raw materials. Mechanical alloying process and the possibility of reaching nanostructure or amorphous phase was investigated. Space holder technique 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 at two different sintering times. The effect of grain size and secondary phases on mechanical properties and phase transformation temperatures was studied.
Results: The results showed that milling for 50 h at 300 rpm has led to amorphous phase and nanocrystallite with 50 nm diameter. Using space holder technique with the appropriate amount of spacer and choosing proper sintering time and temperature, the specimens with 70% porosity were produced. Furthermore, nanoscale grain size can lead to R phase transition. In fact, one of the effects of reaching to nanostructure is occurring R transformation due to high dislocation density and high grain boundaries surface. Nanostructured sample with 70% porosity was shown 5% superelasticity in the cyclic pressure test.
Conclusions: As the results showed, one of the advantages of porous samples is their elastic modulus which is more similar to the bone than other metallic implants.

Graphical Abstract

Synthesis of Porous Nanostructure NiTi Implant and Measurement of Thermomechanical Properties


1.Kaynak Y, Karaca H, Noebe R, Jawahir I. Analysis of tool-wear and cutting force components in dry, preheated, and cryogenic machining of NiTi shape memory alloys, Procedia CIRP. 2013;8:498-503.
2.Ren H, Anuraj B, Dupont PE. Varying ultrasound power level to distinguish surgical instruments and tissue. Medical & biological engineering & computing, 2018;56(3):453-67.
3.La Rosa G, Savio FL, Pedullà E, Rapisarda E. A new torquemeter to measure the influence of heat-treatment on torsional resistance of NiTi endodontic instruments. Engineering Failure Analysis, 2017;82:446-57.
4.Gurley A, Lambert TR, Beale D, Broughton R. Dual measurement self-sensing technique of NiTi actuators for use in robust control. Smart Materials and Structures, 2017;26(10):105050.
5.Hartl DJ, Lagoudas DC. Aerospace applications of shape memory alloys. Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, 2007;221(4):535-52.
6.Alarcon E, Heller L, Chirani SA, Šittner P, Kopeček J, Saint-Sulpice L, et al. Fatigue performance of superelastic NiTi near stress-induced martensitic transformation. International Journal of Fatigue, 2017;95:76-89.
7.Ghasemi A, Hosseini S, Sadrnezhaad S. Pore control in SMA NiTi scaffolds via space holder usage. Materials Science and Engineering: C, 2012;32(5):1266-70.
8.Itin V, Gyunter V, Shabalovskaya S, Sachdeva R. Mechanical properties and shape memory of porous nitinol. Materials characterization, 1994;32(3):179-87.
9.Andani MT, Saedi S, Turabi AS, Karamooz M, Haberland C, Karaca HE, et al. Mechanical and shape memory properties of porous Ni 50.1 Ti 49.9 alloys manufactured by selective laser melting. Journal of the Mechanical Behavior of Biomedical Materials, 2017;68:224-31.
10.Xia M, Liu P, Sun Q. Grain size dependence of Young’s modulus and hardness for nanocrystalline NiTi shape memory alloy. Materials Letters, 2018;211:352-5.
11.Zhu S, Yang X, Fu D, Zhang L, Li C, Cui Z. Stress–strain behavior of porous NiTi alloys prepared by powders sintering. Materials Science and Engineering: A, 2005;408(1):264-8.
12.Farvizi M, Akbarpour MR, Yoon EY, Kim HS. Effect of high-pressure torsion on the microstructure and wear behavior of NiTi alloy. Metals and Materials International, 2015;21(5):891-6.
13.Guoxin H, Lixiang Z, Yunliang F, Yanhong L. Fabrication of high porous NiTi shape memory alloy by metal injection molding. Journal of materials processing technology, 2008;206(1):395-9.
14.Zhang L, Zhang Y, Jiang Y, Zhou R. Superelastic behaviors of biomedical porous NiTi alloy with high porosity and large pore size prepared by spark plasma sintering. Journal of Alloys and Compounds, 2015;644:513-22.
15.Kaya M, Orhan N, Tosun G. The effect of the combustion channels on the compressive strength of porous NiTi shape memory alloy fabricated by SHS as implant material. Current opinion in solid state and materials science, 2010;14(1):21-5.
16.Tian B, Tong Y, Chen F, Liu Y, Zheng Y. Phase transformation of NiTi shape memory alloy powders prepared by ball milling. Journal of Alloys and Compounds, 2009;477(1):576-9.
17.Mousavi T, Karimzadeh F, Abbasi M. Synthesis and characterization of nanocrystalline NiTi intermetallic by mechanical alloying. Materials Science and Engineering: A, 2008;487(1):46-51.
18.Suryanarayana C. Mechanical alloying and milling. Progress in materials science, 2001;46(1):1-184.
19.Gu Y, Goh C, Goi L, Lim C, Jarfors A, Tay B, et al. Solid state synthesis of nanocrystalline and/or amorphous 50Ni–50Ti alloy. Materials Science and Engineering: A, 2005;392(1):222-8.
20.Suryanarayana C, Grant N. A Practical Approach Plenum Press. New York. 1998.
21.Waitz T, Karnthaler H. Martensitic transformation of NiTi nanocrystals embedded in an amorphous matrix. Acta Materialia, 2004;52(19):5461-9.
22.Shi X, Guo F, Zhang J, Ding H, Cui L. Grain size effect on stress hysteresis of nanocrystalline NiTi alloys. Journal of Alloys and Compounds, 2016;688:62-8.
23.Zehetbauer MJ, Zhu YT. Bulk nanostructured materials: John Wiley & Sons; 2009.