Abstract:Severe plastic deformation is the best method for processing ultrafine grained (UFG) high strength commercially pure titanium (CP Ti) without any toxic and harmful elements for biomedical implants. Besides, because of the vital importance of the surface bioactivity of a medical implant, this paper studies the effect of Plasma electrolytic oxidation (PEO) process of UFG CP Ti processed by equal channel angular pressing (ECAP). The aqueous electrolyte chosen for PEO process was prepared by mixing 0.15 M calcium … Show more
“…The PSE of the optimally printed Ti-based nanocomposites reaches 16.8 GPa·%, showing a maximum 350% improvement in PSE as relative to conventionally processed unreinforced CP-Ti. Figure 5 Tensile Properties of Laser 3D-Printed In Situ Ti-Based Nanocomposite Parts (A) A summary of tensile strength versus fracture elongation of Ti processed by various methods, including our work (red region), laser additive manufactured Ti with refined microstructure (purple region) ( Herzog et al., 2016 ; Wysocki et al., 2017 ; Zhang et al., 2008 ), conventional coarse-grained Ti processed by casting and forging (yellow region) ( Koike et al., 2011 ; Stolyarov et al., 2001 ; Xu and Zhu, 2012 ; Niinomi, 1998 ; Reshadi et al., 2017 ; Figueiredo et al., 2014 ; Zhao et al., 2010 ; Zinelis, 2000 ), Ti strengthened through plastic deformation with the formation of nanostructure (blue region) ( Gunderov et al., 2013 ; Liang et al., 2015 ). The error bar of each experimental datum from our work is depicted in Figure S5 .…”
Summary
Zero- to two-dimensional nanomaterials have been incorporated into metal-matrices to improve the strength of metals, but challengingly, high-volume-fraction nanomaterials are difficult to disperse uniformly in metal matrices, severely degrading the ductility of conventionally processed metals. Here, a considerably dense uniform dispersion of
in situ
formed nanoscale lamellar TiC reinforcement (16.1 wt %) in Ti matrix is achieved through laser-tailored 3D printing and complete reaction of Ti powder with a small amount (1.0 wt %) of carbon nanotubes (CNTs). An enhanced tensile strength of 912 MPa and an outstanding fracture elongation of 16% are simultaneously achieved for laser-printed components, showing a maximum 350% improvement in “product of strength and elongation” compared with conventional Ti.
In situ
nanoscale TiC reinforcement favors the formation of ultrafine equiaxed Ti grains and metallurgically coherent interface with minimal lattice misfit between TiC lamellae and Ti matrix. Our approach hopefully provides a feasible way to broaden structural applications of CNTs in load-bearing Ti-based engineering components via laser-tailored reorganization with Ti.
“…The PSE of the optimally printed Ti-based nanocomposites reaches 16.8 GPa·%, showing a maximum 350% improvement in PSE as relative to conventionally processed unreinforced CP-Ti. Figure 5 Tensile Properties of Laser 3D-Printed In Situ Ti-Based Nanocomposite Parts (A) A summary of tensile strength versus fracture elongation of Ti processed by various methods, including our work (red region), laser additive manufactured Ti with refined microstructure (purple region) ( Herzog et al., 2016 ; Wysocki et al., 2017 ; Zhang et al., 2008 ), conventional coarse-grained Ti processed by casting and forging (yellow region) ( Koike et al., 2011 ; Stolyarov et al., 2001 ; Xu and Zhu, 2012 ; Niinomi, 1998 ; Reshadi et al., 2017 ; Figueiredo et al., 2014 ; Zhao et al., 2010 ; Zinelis, 2000 ), Ti strengthened through plastic deformation with the formation of nanostructure (blue region) ( Gunderov et al., 2013 ; Liang et al., 2015 ). The error bar of each experimental datum from our work is depicted in Figure S5 .…”
Summary
Zero- to two-dimensional nanomaterials have been incorporated into metal-matrices to improve the strength of metals, but challengingly, high-volume-fraction nanomaterials are difficult to disperse uniformly in metal matrices, severely degrading the ductility of conventionally processed metals. Here, a considerably dense uniform dispersion of
in situ
formed nanoscale lamellar TiC reinforcement (16.1 wt %) in Ti matrix is achieved through laser-tailored 3D printing and complete reaction of Ti powder with a small amount (1.0 wt %) of carbon nanotubes (CNTs). An enhanced tensile strength of 912 MPa and an outstanding fracture elongation of 16% are simultaneously achieved for laser-printed components, showing a maximum 350% improvement in “product of strength and elongation” compared with conventional Ti.
In situ
nanoscale TiC reinforcement favors the formation of ultrafine equiaxed Ti grains and metallurgically coherent interface with minimal lattice misfit between TiC lamellae and Ti matrix. Our approach hopefully provides a feasible way to broaden structural applications of CNTs in load-bearing Ti-based engineering components via laser-tailored reorganization with Ti.
“…Since Ti-6Al-4V possesses greater mechanical strength than titanium, it is the preferred material for hard tissue implants [ 3 ]. However, titanium alloy contains elements that are harmful to the human body, which may cause allergies, inflammation, and malignant reactions, limiting its further application in the field of biomedicine [ 4 , 5 ]. In recent years, distinct progress has been made in studies on ultrafine-grained titanium processed by equal-channel angular pressing (ECAP), which possesses favorable mechanical performance and does not contain elements that are toxic to the human body [ 6 , 7 ].…”
Ultrafine-grained pure titanium prepared by equal-channel angular pressing has favorable mechanical performance and does not contain alloy elements that are toxic to the human body. It has potential clinical value in applications such as cardiac valve prostheses, vascular stents, and hip prostheses. To overcome the material’s inherent thrombogenicity, surface-coating modification is a crucial pathway to enhancing blood compatibility. An electrolyte solution of sodium silicate + sodium polyphosphate + calcium acetate and the micro-arc oxidation (MAO) technique were employed for in situ oxidation of an ultrafine-grained pure titanium surface. A porous coating with anatase- and rutile-phase TiO2 was generated and wettability and blood compatibility were examined. The results showed that, in comparison with ultrafine-grained pure titanium substrate, the MAO coating had a rougher surface, smaller contact angles for distilled water and higher surface energy. MAO modification effectively reduced the hemolysis rate; extended the dynamic coagulation time, prothrombin time (PT), and activated partial thromboplastin time (APTT); reduced the amount of platelet adhesion and the degree of deformation; and enhanced blood compatibility. In particular, the sample with an oxidation time of 9 min possessed the highest surface energy, largest PT and APTT values, smallest hemolysis rate, less platelet adhesion, a lesser degree of deformation, and more favorable blood compatibility. The MAO method can significantly enhance the blood compatibility of ultrafine-grained pure titanium, increasing its potential for practical applications.
“…However, since most of the common alloying elements used in these alloys, such as Al and V, are toxic to human health, many attempts have been made to find a substitute for the Ti-6Al-4V alloy. In recent years, there is a high tendency to use commercially pure titanium (CP-Ti) which has a lower cost and a better-expected corrosion resistance than Ti-6Al-4V, but its yield strength and ultimate tensile strength are much lower [1,2]. At present, the mechanical properties of CP-Ti grades can be improved to the same or sometimes better than Ti-6Al-4V by grain refinement, commonly achieved via severe plastic deformation (SPD) methods [3][4][5].…”
In this study, combined multi pass equal channel angular pressing (ECAP), and subsequent warm extrusion at different temperatures are performed on commercial purity titanium. Mechanical and microstructural evolutions are then investigated. Since it was observed that the four passes ECAP processed sample showed the best strength and reasonable elongation, this sample was selected for studying the extrusion temperature effects on the structure and mechanical properties of Grade 2 titanium. Therefore, the 4th passes ECAP processed sample was extruded at different temperatures of 300 °C, 350 °C, 400 °C, 450 °C and 500 °C. The result revealed that the best mechanical properties were achieved from the specimen processed by four passes ECAP followed by warm extrusion at 300°C. The strength, and hardness of this sample were considerably improved in comparison with that of the unprocessed sample. Also, its ultra-fine grained and nanograined microstructure were homogeneous, with a grain size ranged from 40-200 nm with an average grain size of about 123 nm. It was seen that the mechanical properties of some samples after applying this combined process (ECAP + warm extrusion) are 2 comparable with those of Grade 5 titanium which is commonly used in medical applications but contains alloying elements that are toxic to human health.
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