Nanostructured Ti-Zr-Pd-Si-(Nb) bulk metallic composites : novel biocompatible materials with superior mechanical strength and elastic recovery

The microstructure, mechanical behaviour, and biocompatibility (cell culture, morphology, and cell adhesion) of nanostructured Ti45 Zr15 Pd35- x Si5 Nbx with x = 0, 5 (at. %) alloys, synthesized by arc melting and subsequent Cu mould suction casting, in the form of rods with 3 mm in diameter, are investigated. Both Ti-Zr-Pd-Si-(Nb) materials show a multi-phase (composite-like) microstructure. The main phase is cubic β-Ti phase (Im3m) but hexagonal α-Ti (P63/mmc), cubic TiPd (Pm3m), cubic PdZr (Fm3m), and hexagonal (Ti, Zr)5 Si3 (P63/mmc) phases are also present. Nanoindentation experiments show that the Ti45 Zr15 Pd30 Si5 Nb5 sample exhibits lower Young's modulus than Ti45 Zr15 Pd35 Si5 . Conversely, Ti45 Zr15 Pd35 Si5 is mechanically harder. Actually, both alloys exhibit larger values of hardness when compared with commercial Ti-40Nb, (HTi-Zr-Pd-Si ≈ 14 GPa, HTi-Zr-Pd-Si-Nb ≈ 10 GPa and HTi-40Nb ≈ 2.7 GPa). Concerning the biological behaviour, preliminary results of cell viability performed on several Ti-Zr-Pd-Si-(Nb) discs indicate that the number of live cells is superior to 94% in both cases. The studied Ti-Zr-Pd-Si-(Nb) bulk metallic system is thus interesting for biomedical applications because of the outstanding mechanical properties (relatively low Young's modulus combined with large hardness), together with the excellent biocompatibility

Novel Ti–Zr–Hf–Fe Nanostructured Alloy for Biomedical Applications

The synthesis and characterization of Ti40Zr20Hf20Fe20 (atom %) alloy, in the form of rods (f = 2 mm), prepared by arc-melting, and subsequent Cu mold suction casting, is presented. The microstructure, mechanical and corrosion properties, as well as in vitro biocompatibility of this alloy, are investigated. This material consists of a mixture of several nanocrystalline phases. It exhibits excellent mechanical behavior, dominated by high strength and relatively low Young’s modulus, and also good corrosion resistance, as evidenced by the passive behavior in a wide potential window and the low corrosion current densities values. In terms of biocompatibility, this alloy is not cytotoxic and preosteoblast cells can easily adhere onto its surface and differentiate into osteoblasts

W cztery oczy o trabancie : z Joanną Hynowską, która pokazuje turystom komunę...

Polska Gazeta Krakowska. - 2011, nr 28 (4 II), dod. Polska Gazeta Krakowska, s.

Biocompatible Ti-based metallic glasses and nanocomposite materials

Aquesta Tesi comprèn la síntesi i caracterització d’aliatges de base Ti amorfs i nanoestructurats. Així, s’han estudiat diversos aliatges amb composició Ti-44.3Nb- 8.7Zr12.3Ta, Ti-31.0Fe-9.0Sn, Ti40Zr20Hf20Fe20, Ti45Zr15Pd35-xSi5Nbx (x = 0, 5%) com a exemples d’aliatges de base Ti nanoestructurats, i el vidre amorf massís Ti40Zr10Cu38Pd12. Aquests materials es van escollir tenint en compte les seves potencials aplicacions com a implants ortopèdics. La primera part d’aquesta Tesi va consistir en la síntesi i caracterització d’aquests aliatges bo i fent especial èmfasi en les correlacions existents en el triangle microestructura – comportament mecànic – biocompatibilitat. En la segona part es van dur a terme tractaments d’irradiació amb feixos d’ions del vidre amorf com a estratègia per modificar les seves propietats superficials i, de retruc, incrementar-ne la compatibilitat biomecànica. Totes les mostres es van sintetitzar per fusió d’arc i posterior emmotllament. Es va dur a terme una caracterització exhaustiva de tipus tèrmic i estructural de les mostres anteriorment mencionades mitjançant calorimetria diferencial d’escombrat (DSC), difracció de raigs X (XRD) i microscòpia electrònica de rastreig i transmissió (SEM, TEM). Tot seguit, els materials es van caracteritzar mecànicament (nanoindentació, mesures acústiques), electroquímicament (assaigs de polarització potenciodinàmica) i biològicament (toxicitat, morfologia, adhesió i diferenciació cel·lular). S’ha vist que l’aliatge nanoestructurat Ti-Nb-Zr-Ta és interessant pel seu baix mòdul de Young (Er = 71 GPa), mentre que el sistema Ti-Fe-Sn destaca per la seva elevada duresa (H = 8.9 GPa). Ensems, l’aliatge Ti-Zr-Pd-Si-Nb posseeix un mòdul de Young relativament baix (Er = 85 GPa) i una duresa elevada (H = 10.4 GPa). En general, quan s’alien amb el Ti elements estabilitzadors tipus (Nb, Ta, Fe i Pd), combinats d’una forma adient, s’aconsegueix reduir del mòdul de Young del material i, al mateix temps, incrementar-ne la duresa. La substitució parcial de Pd per Nb és una estratègia eficaç per disminuir el mòdul elàstic (es va observar una davallada de fins a un 30% en el valor de Er) del sistema Ti-Zr-Pd-Si i, simultàniament, reduir-ne el cost. D’altra banda, s’obtenen valors elevats de duresa, com és el cas dels aliatges Ti-Zr-Pd-Si-(Nb) i Ti-Zr-Hf-Fe, quan s’aconsegueix tenir una microestructura formada per una mescla de nanofases. Val a dir que tots els aliatges estudiats presenten una resistència al desgast superior a la de l’aliatge d’ús comercial Ti-6Al-4V. Així mateix, no s’ha observat un deteriorament significatiu dels materials en els estudis de corrosió electroquímica, malgrat que es va detectar atac per picadura en el vidre amorf massís Ti40Zr10Cu38Pd12. Els assajos biològics van demostrar que tant les cèl·lules preosteoblast de ratolí com humanes s’adhereixen molt bé sobre la superfícies dels aliatges i que són capaces de diferenciar-se en osteoblasts, en part com a conseqüència de la presència d’elements no tòxics en la seva composició. En aquesta Tesi també es demostra que per a fluències d’ions i energies incidents suficientment baixes, es preserva el caràcter amorf del vidre massís Ti40Zr10Cu38Pd12 després de la irradiació a temperatura ambient. En canvi, quan aquestes condicions d’irradiació s’apliquen a una temperatura propera a Tg (620 K), s’indueix una nanocristal·lització parcial a la superfície del material. Això fa que ocorrin canvis en les propietats mecàniques que són totalment oposats dels observats a temperatura ambient (reducció de la duresa i del mòdul de Young probablement a causa de l’increment de concentració del volum lliure). En particular, després del tractament amb feixos d’ions a alta temperatura, s’observa un increment tant de la duresa com del mòdul de Young. Els resultats indiquen, per tant, que bo i modulant tant la temperatura de la mostra com les condicions d’irradació, poden controlar-se les propietats del material resultant per tal de satisfer demandes tecnològiques específiques, com ara de tipus mecànic.This Thesis covers the synthesis and overall characterization of Ti-based glassy alloys and nanostructured materials. Several Ti-based nanostructured alloys with nominal composition, Ti-44.3Nb-8.7Zr12.3Ta, Ti-31.0Fe-9.0Sn, Ti40Zr20Hf20Fe20, Ti45Zr15Pd35-xSi5Nbx (x = 0, 5%), and Ti-based bulk metallic glass (BMG), Ti40Zr10Cu38Pd12, were investigated. These materials were chosen due to their potential applications as orthopedic implants. The first part of the study focused on the synthesis and characterization of these alloys by paying special attention to the correlation triangle microstructure-mechanical behaviourbiocompatibility. The second part was devoted to ion-irradiation treatment of the BMG material as a means to modify the surface properties and therefore increase its biomechanical compatibility. All samples were produced by arc melting and subsequenct suction casting. The in-depth thermal and structural characterization of above-mentioned samples was carried out by means of differencial scanning calorymetry (DSC) and x-ray diffraction (XRD), together with scanning and transmission electron miscroscopies (SEM, TEM). Subsequently, the samples were subjected to mechanical (nanoindentation, acoustic measurement), electrochemical (potentiodynamic polarization tests) and biological (cytotoxicity, cell morphology, adhesion and differentiation) analysis. It is shown that Ti-Nb-Zr-Ta nanostructured alloy is appealing because of its low Young’s modulus (Er = 71 GPa), whereas the Ti-Fe-Sn system is interesting because of its large hardness (H = 8.9 GPa). Meanwhile Ti-Zr-Pd-Si-Nb alloy possesses relatively low Young’s modulus (Er = 85 GPa) and high hardness (H = 10.4 GPa). The lowering of Young’s modulus and the increase in hardness was achieved through proper combination of - stabilizer elements (Nb, Ta, Fe and Pd) alloyed with Ti. Partial replacement of Pd by Nb is a convenient strategy to decrease the Young’s modulus (almost a drop of 30% in Er was observed) of the Ti-Zr-Pd-Si system, and to reduce costs. On the other hand, a microstructure consisting of a mixture of nanophases gives rise to large hardness values, as is the case of Ti-Zr-Pd-Si-(Nb) and Ti-Zr-Hf-Fe alloys. Additionally, all studied alloys exhibit better wear resistance than that of commercially used Ti-6Al-4V. None of the studied materials showed extensive corrosion damage when tested electrochemically, although pitting was observed in Ti40Zr10Cu38Pd12 BMG. The biological assays demonstrated that either preosteoblast mouse or human cells adhered very well to the surface of the studied alloys and were able to differentiate into osteoblasts. This is due, to some extent, to the presence of safe (i.e., non-toxic) elements in alloys’ composition. In this Thesis, it is also demonstrated that for sufficiently low ion fluencies and low incident energies, the glassy structure of the as-cast Ti40Zr10Cu38Pd12 BMG is preserved after irradiation at room temperature (RT). Conversely, the same mild irradiation conditions applied at a temperature close to Tg (620 K) induce partial nanocrystallization at the surface of the material. As a consequence, the changes in mechanical properties observed after irradiation at RT (reduction of hardness and Young’s modulus, presumably due to the increase of the free volume concentration) are opposite to those observed after temperatureassisted ion irradiation processes. Namely, an enhancement is observed after hightemperature irradiation of the Ti-based glassy alloy. Hence, these results indicate that, by tuning both the sample temperature and the irradiation conditions, the properties of the resulting material can be controlled in order to meet specific technological demands, such as mechanical performance

Biocompatible Ti-based metallic glasses and nanocomposite materials

Aquesta Tesi comprèn la síntesi i caracterització d'aliatges de base Ti amorfs i nanoestructurats. Així, s'han estudiat diversos aliatges amb composició Ti-44.3Nb- 8.7Zr12.3Ta, Ti-31.0Fe-9.0Sn, Ti40Zr20Hf20Fe20, Ti45Zr15Pd35-xSi5Nbx (x = 0, 5%) com a exemples d'aliatges de base Ti nanoestructurats, i el vidre amorf massís Ti40Zr10Cu38Pd12. Aquests materials es van escollir tenint en compte les seves potencials aplicacions com a implants ortopèdics. La primera part d'aquesta Tesi va consistir en la síntesi i caracterització d'aquests aliatges bo i fent especial èmfasi en les correlacions existents en el triangle microestructura - comportament mecànic - biocompatibilitat. En la segona part es van dur a terme tractaments d'irradiació amb feixos d'ions del vidre amorf com a estratègia per modificar les seves propietats superficials i, de retruc, incrementar-ne la compatibilitat biomecànica. Totes les mostres es van sintetitzar per fusió d'arc i posterior emmotllament. Es va dur a terme una caracterització exhaustiva de tipus tèrmic i estructural de les mostres anteriorment mencionades mitjançant calorimetria diferencial d'escombrat (DSC), difracció de raigs X (XRD) i microscòpia electrònica de rastreig i transmissió (SEM, TEM). Tot seguit, els materials es van caracteritzar mecànicament (nanoindentació, mesures acústiques), electroquímicament (assaigs de polarització potenciodinàmica) i biològicament (toxicitat, morfologia, adhesió i diferenciació cel·lular). S'ha vist que l'aliatge nanoestructurat Ti-Nb-Zr-Ta és interessant pel seu baix mòdul de Young (Er = 71 GPa), mentre que el sistema Ti-Fe-Sn destaca per la seva elevada duresa (H = 8.9 GPa). Ensems, l'aliatge Ti-Zr-Pd-Si-Nb posseeix un mòdul de Young relativament baix (Er = 85 GPa) i una duresa elevada (H = 10.4 GPa). En general, quan s'alien amb el Ti elements estabilitzadors tipus (Nb, Ta, Fe i Pd), combinats d'una forma adient, s'aconsegueix reduir del mòdul de Young del material i, al mateix temps, incrementar-ne la duresa. La substitució parcial de Pd per Nb és una estratègia eficaç per disminuir el mòdul elàstic (es va observar una davallada de fins a un 30% en el valor de Er) del sistema Ti-Zr-Pd-Si i, simultàniament, reduir-ne el cost. D'altra banda, s'obtenen valors elevats de duresa, com és el cas dels aliatges Ti-Zr-Pd-Si-(Nb) i Ti-Zr-Hf-Fe, quan s'aconsegueix tenir una microestructura formada per una mescla de nanofases. Val a dir que tots els aliatges estudiats presenten una resistència al desgast superior a la de l'aliatge d'ús comercial Ti-6Al-4V. Així mateix, no s'ha observat un deteriorament significatiu dels materials en els estudis de corrosió electroquímica, malgrat que es va detectar atac per picadura en el vidre amorf massís Ti40Zr10Cu38Pd12. Els assajos biològics van demostrar que tant les cèl·lules preosteoblast de ratolí com humanes s'adhereixen molt bé sobre la superfícies dels aliatges i que són capaces de diferenciar-se en osteoblasts, en part com a conseqüència de la presència d'elements no tòxics en la seva composició. En aquesta Tesi també es demostra que per a fluències d'ions i energies incidents suficientment baixes, es preserva el caràcter amorf del vidre massís Ti40Zr10Cu38Pd12 després de la irradiació a temperatura ambient. En canvi, quan aquestes condicions d'irradiació s'apliquen a una temperatura propera a Tg (620 K), s'indueix una nanocristal·lització parcial a la superfície del material. Això fa que ocorrin canvis en les propietats mecàniques que són totalment oposats dels observats a temperatura ambient (reducció de la duresa i del mòdul de Young probablement a causa de l'increment de concentració del volum lliure). En particular, després del tractament amb feixos d'ions a alta temperatura, s'observa un increment tant de la duresa com del mòdul de Young. Els resultats indiquen, per tant, que bo i modulant tant la temperatura de la mostra com les condicions d'irradació, poden controlar-se les propietats del material resultant per tal de satisfer demandes tecnològiques específiques, com ara de tipus mecànic.This Thesis covers the synthesis and overall characterization of Ti-based glassy alloys and nanostructured materials. Several Ti-based nanostructured alloys with nominal composition, Ti-44.3Nb-8.7Zr12.3Ta, Ti-31.0Fe-9.0Sn, Ti40Zr20Hf20Fe20, Ti45Zr15Pd35-xSi5Nbx (x = 0, 5%), and Ti-based bulk metallic glass (BMG), Ti40Zr10Cu38Pd12, were investigated. These materials were chosen due to their potential applications as orthopedic implants. The first part of the study focused on the synthesis and characterization of these alloys by paying special attention to the correlation triangle microstructure-mechanical behaviourbiocompatibility. The second part was devoted to ion-irradiation treatment of the BMG material as a means to modify the surface properties and therefore increase its biomechanical compatibility. All samples were produced by arc melting and subsequenct suction casting. The in-depth thermal and structural characterization of above-mentioned samples was carried out by means of differencial scanning calorymetry (DSC) and x-ray diffraction (XRD), together with scanning and transmission electron miscroscopies (SEM, TEM). Subsequently, the samples were subjected to mechanical (nanoindentation, acoustic measurement), electrochemical (potentiodynamic polarization tests) and biological (cytotoxicity, cell morphology, adhesion and differentiation) analysis. It is shown that Ti-Nb-Zr-Ta nanostructured alloy is appealing because of its low Young's modulus (Er = 71 GPa), whereas the Ti-Fe-Sn system is interesting because of its large hardness (H = 8.9 GPa). Meanwhile Ti-Zr-Pd-Si-Nb alloy possesses relatively low Young's modulus (Er = 85 GPa) and high hardness (H = 10.4 GPa). The lowering of Young's modulus and the increase in hardness was achieved through proper combination of - stabilizer elements (Nb, Ta, Fe and Pd) alloyed with Ti. Partial replacement of Pd by Nb is a convenient strategy to decrease the Young's modulus (almost a drop of 30% in Er was observed) of the Ti-Zr-Pd-Si system, and to reduce costs. On the other hand, a microstructure consisting of a mixture of nanophases gives rise to large hardness values, as is the case of Ti-Zr-Pd-Si-(Nb) and Ti-Zr-Hf-Fe alloys. Additionally, all studied alloys exhibit better wear resistance than that of commercially used Ti-6Al-4V. None of the studied materials showed extensive corrosion damage when tested electrochemically, although pitting was observed in Ti40Zr10Cu38Pd12 BMG. The biological assays demonstrated that either preosteoblast mouse or human cells adhered very well to the surface of the studied alloys and were able to differentiate into osteoblasts. This is due, to some extent, to the presence of safe (i.e., non-toxic) elements in alloys' composition. In this Thesis, it is also demonstrated that for sufficiently low ion fluencies and low incident energies, the glassy structure of the as-cast Ti40Zr10Cu38Pd12 BMG is preserved after irradiation at room temperature (RT). Conversely, the same mild irradiation conditions applied at a temperature close to Tg (620 K) induce partial nanocrystallization at the surface of the material. As a consequence, the changes in mechanical properties observed after irradiation at RT (reduction of hardness and Young's modulus, presumably due to the increase of the free volume concentration) are opposite to those observed after temperatureassisted ion irradiation processes. Namely, an enhancement is observed after hightemperature irradiation of the Ti-based glassy alloy. Hence, these results indicate that, by tuning both the sample temperature and the irradiation conditions, the properties of the resulting material can be controlled in order to meet specific technological demands, such as mechanical performance

Comparative study of the microstructure and elastic/mechanical properties of Ti-Zr-Cu-Pd-(Nb) and Ti-Zr-Fe-(Hf) alloys

Ti-based metallic glasses are particularly promising lightweight metallic materials for biomedical applications because of their high strength, excellent corrosion resistance and good biocompatibility. However, there are still some limitations e.g. lack of plasticity, which have to be considered in order to use these alloys for implants. Recent reports on Ti-based composites have demonstrated that desired mechanical properties combining high strength, tensile ductility and excellent fracture toughness can be achieved by proper alloy design and microstructure control. The aim of our work is to find alloys with the mechanical properties close to those of bone, containing neither toxic nor allergic elements and possessing large hardness and low Young´s modulus values, thus favoring their biomechanical compatibility with bone

Influence of the irradiation temperature on the surface structure and physical/chemical properties of Ar ion-irradiated bulk metallic glasses

Surface treatments using multiple Ar ion irradiation processes with a maximum energy and fluence of 200 keV and 1 × 1016 ions/cm 2, respectively, have been performed on two different metallic glasses: Zr55Cu28Al10Ni7 and Ti 40Zr10Cu38Pd12. Analogous irradiation procedures have been carried out at room temperature (RT) and at T = 620 K (0.9 Tg, where Tg denotes the glass transition). The structure, mechanical behavior, wettability and corrosion resistance of the irradiated alloys have been compared with the properties of the as-cast and annealed (T = 620 K) non-irradiated specimens. While ion irradiation at RT does not significantly alter the amorphous structure of the alloys, ion irradiation close to Tg promotes decomposition/nanocrystallization. Consequently, the hardness (H) and reduced Young's modulus (Er) decrease after irradiation at RT but they both increase after irradiation at 620 K. While annealing close to Tg increases the hydrophobicity of the samples, irradiation induces virtually no changes in the contact angle when comparing with the as-cast state. Concerning the corrosion resistance, although not much effect is found after irradiation at RT, an improvement is observed after irradiation at 620 K, particularly for the Ti-based alloy. These results are of practical interest in order to engineer appropriate surface treatments based on ion irradiation, aimed at specific functional applications of bulk metallic glasses. © 2014 Elsevier B.V. All rights reserved.status: publishe

Effect of Surface Modifications of Ti40Zr10Cu38Pd12 Bulk Metallic Glass and Ti-6Al-4V Alloy on Human Osteoblasts In Vitro Biocompatibility.

The use of biocompatible materials, including bulk metallic glasses (BMGs), for tissue regeneration and transplantation is increasing. The good mechanical and corrosion properties of Ti40Zr10Cu38Pd12 BMG and its previously described biocompatibility makes it a potential candidate for medical applications. However, it is known that surface properties like topography might play an important role in regulating cell adhesion, proliferation and differentiation. Thus, in the present study, Ti40Zr10Cu38Pd12 BMG and Ti6-Al-4V alloy were surface-modified electrochemically (nanomesh) or physically (microscratched) to investigate the effect of material topography on human osteoblasts cells (Saos-2) adhesion, proliferation and differentiation. For comparative purposes, the effect of mirror-like polished surfaces was also studied. Electrochemical treatments led to a highly interconnected hierarchical porous structure rich in oxides, which have been described to improve corrosion resistance, whereas microscratched surfaces showed a groove pattern with parallel trenches. Cell viability was higher than 96% for the three topographies tested and for both alloy compositions. In all cases, cells were able to adhere, proliferate and differentiate on the alloys, hence indicating that surface topography plays a minor role on these processes, although a clear cell orientation was observed on microscratched surfaces. Overall, our results provide further evidence that Ti40Zr10Cu38Pd12 BMG is an excellent candidate, in the present two topographies, for bone repair purposes

Nanostructured β-phase Ti–31.0Fe–9.0Sn and sub-μm structured Ti–39.3Nb–13.3Zr–10.7Ta alloys for biomedical applications: Microstructure benefits on the mechanical and corrosion performances

Nanostructured Ti–31.0Fe–9.0Sn and sub-micrometer structured Ti–39.3Nb–13.3Zr–10.7Ta (wt.%) β-type alloys, exhibiting different microstructures and dissimilar mechanical properties, have been prepared by copper mold casting. The microstructure, mechanical behavior and corrosion resistance, in simulated body fluid, of both alloys have been investigated and compared to those of commercial Ti–6Al–4V. Nanoindentation experiments reveal that the Ti–31.0Fe–9.0Sn rods exhibit very large hardness (H ≈ 9 GPa) and high Young's modulus. Conversely, the Ti–39.3Nb–13.3Zr–10.7Ta alloy is mechanically softer but it is interesting for biomedical application because of its rather low Young's modulus (E ≈ 71 GPa). Concerning the corrosion performance, Ti–35Nb–7Zr–5Ta shows a corrosion behavior comparable to Ti–Al6–V4, with no potential breakdown up to 0.4 V vs. Ag|AgCl. On the contrary, the Ti–31.0Fe–9.0Sn alloy exhibits a more anodic corrosion potential, but the value is still less negative than for pure elemental Fe and Ti. From all these properties and because of the absence of toxic elements in the compositions, the Ti–39.3Nb–13.3Zr–10.7Ta and Ti–31.0Fe–9.0Sn alloys are attractive for use as metallic biomaterials