A review of shape memory alloy research, applications and opportunities

https://material.karlov.mff.cuni.cz/people/janecek/studenti/FyzMetNano/Estrin_AM61_2013_782.pdf

Extreme grain refinement by severe plastic deformation: A wealth of challenging science

https://www.tpbin.com/Uploads/Subjects/643149a0-8194-4c67-bf05-73fae6f0d14f.pdf

Development of new metallic alloys for biomedical applications

Martensitic transformation, shape memory effect and superelasticity of Ti-Nb binary alloys

Ti-based alloys are finding ever-increasing applications in biomaterials due to their excellent mechanical, physical and biological performance. Nowdays, low modulus β-type Ti-based alloys are still being developed. Meanwhile, porous Ti-based alloys are being developed as an alternative orthopedic implant material, as they can provide good biological fixation through bone tissue ingrowth into the porous network. This paper focuses on recent developments of biomedical Ti-based alloys. It can be divided into four main sections. The first section focuses on the fundamental requirements titanium biomaterial should fulfill and its market and application prospects. This section is followed by discussing basic phases, alloying elements and mechanical properties of low modulus β-type Ti-based alloys. Thermal treatment, grain size, texture and properties in Ti-based alloys and their limitations are dicussed in the third section. Finally, the fourth section reviews the influence of microstructural configurations on mechanical properties of porous Ti-based alloys and all known methods for fabricating porous Ti-based alloys. This section also reviews prospects and challenges of porous Ti-based alloys, emphasizing their current status, future opportunities and obstacles for expanded applications. Overall, efforts have been made to reveal the latest scenario of bulk and porous Ti-based materials for biomedical applications.

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New Developments of Ti-Based Alloys for Biomedical Applications

Mechanical properties and shape memory behavior of Ti-(20–29)at%Nb alloys were investigated in order to develop Ni-free biomedical shape memory alloys. The Ti-Nb alloys were fabricated by arc melting method. The ingots were cold-rolled with a reduction up to 95% in thickness and then solution treated at 1173 K for 1.8 ks. The martensitic transformation temperature decreased by 43 K per 1 at% increase of Nb content. The shape memory effect and superelastic behavior were observed at room temperature in the Ti-(22–25)at%Nb alloys and Ti-(25.5– 27)at%Nb alloys, respectively. A small enthalpy of the martensitic transformation and a large difference between Ms and Mf were observed in the Ti-Nb alloys compared to Ti-Ni shape memory alloys. The maximum recovered strain of 3% was obtained at room temperature in solution treated Ti-(25–27)at%Nb alloys. The heat treatment at 573 K for 3.6 ks stabilized superelastic behavior of Ti-Nb alloys by increasing the critical stress for slip.

Mechanical Properties and Shape Memory Behavior of Ti-Nb Alloys

Shape memory characteristics of Ti–22Nb–(2–8)Zr(at.%) biomedical alloys were investigated by using tensile tests and X-ray diffraction (XRD) measurement. The alloy ingots were fabricated by an arc melting method. The ingots were cold-rolled by a reduction up to 95% in thickness at room temperature. All the alloys were solution-treated at 1173 K for 1.8 ks. The alloys subjected to the solution treatment exhibited large elongations ranging between 28 and 40%. The martensitic transformation temperature decreased by 38 K with 1 at.% increase of Zr content. The maximum recovered strain of 4.3% was obtained in the Ti–22Nb–4Zr(at.%) alloy. Ti–22Nb–(2–4)Zr(at.%) and Ti–22Nb–6Zr(at.%) alloys exhibited stable shape memory effect and superelastic behavior at room temperature, respectively.

Shape memory characteristics of Ti–22Nb–(2–8)Zr(at.%) biomedical alloys

Texture and shape memory behavior of Ti–22Nb–6Ta alloy

In order to develop new biomedical shape memory alloys, mechanical properties and shape memory behavior of Ti-22Nb-(0.5-2.0)O(at%) alloys were investigated by tensile tests at various temperatures and X-ray diffraction measurement. The Ti-Nb-O alloys were fabricated by an arc melting method and then homogenized at 1273 K for 7.2ks. The ingots were cold-rolled with a reduction up to 98.5% in thickness and solution treated at 1173 K for 1.8 ks. The fracture stress of both as-rolled specimen and solution treated specimen increased with increasing oxygen content. A fracture stress of 1.37 GPa was obtained in the as-rolled Ti-22Nb-20 alloy. The martensitic transformation temperature decreased by 160 K per 1 at% increase of oxygen content. Superior shape memory effect and superelastic behavior were observed at room temperature in the Ti-22Nb-(0.5-1.5)O alloys. The addition of oxygen stabilized superelastic behavior of Ti-Nb alloys by increasing the critical stress for permanent deformation. The maximum shape recovery strain of 4.0% and the critical stress of 900 MPa for permanent deformation were obtained in the Ti-22Nb-0.5O and Ti-22Nb-1.50 alloys, respectively.

/pdf/shape-memory-behavior-of-ti-22nb-0-5-2-0-o-at-biomedical-1xwnbrnnz2.pdf

Jae Il Kim

Papers

Martensitic transformation, shape memory effect and superelasticity of Ti-Nb binary alloys

Mechanical Properties and Shape Memory Behavior of Ti-Nb Alloys

Shape memory characteristics of Ti–22Nb–(2–8)Zr(at.%) biomedical alloys

Texture and shape memory behavior of Ti–22Nb–6Ta alloy

Shape Memory Behavior of Ti–22Nb–(0.5–2.0)O(at%) Biomedical Alloys