The Equal Channel Angular Extrusion in Grade 2 and 4 commercially pure titanium raises the yield ... more The Equal Channel Angular Extrusion in Grade 2 and 4 commercially pure titanium raises the yield strength, ultimate tensile strength, elongation, fatigue limit, besides to attend the requirements of torque and angle of rupture for implants.
A metastable beta TMZF alloy was tested by isothermal compression under different conditions of d... more A metastable beta TMZF alloy was tested by isothermal compression under different conditions of deformation temperature (923 to 1173 K), strain rate (0.172, 1.72, and 17.2 s−1), and a constant strain of 0.8. Stress–strain curves, constitutive constants calculations, and microstructural analysis were performed to understand the alloy’s hot working behavior in regards to the softening and hardening mechanisms operating during deformation. The primary softening mechanism was dynamic recovery, promoting dynamic recrystallization delay during deformation at higher temperatures and low strain rates. Mechanical twinning was an essential deformation mechanism of this alloy, being observed on a nanometric scale. Spinodal decomposition evidence was found to occur during hot deformation. Different models of phenomenological constitutive equations were tested to verify the effectiveness of flow stress prediction. The stress exponent n, derived from the strain-compensated Arrhenius-type constitu...
Resumo: O presente trabalho teve como objetivo a determinação dos parâmetros ótimos do processo d... more Resumo: O presente trabalho teve como objetivo a determinação dos parâmetros ótimos do processo de manufatura aditiva de Fusão Seletiva a Laser (FSL) para o aço 316L visando a obtenção de peças com alta densidade, utilizando equipamento fabricado no Brasil. Foi realizada também uma completa caracterização estrutural tanto da matéria prima utilizada (pó comercial) quanto das peças mais densas obtidas. As propriedades mecânicas das peças produzidas por FSL também foram avaliadas e comparadas com peça fabricada de forma convencional. Foi observado que a densidade das peças aumenta com o aumento da densidade volumétrica de energia fornecida pelo laser até atingir um patamar de máxima densidade. Um modelo polinomial foi proposto correlacionando a densidade volumétrica de energia utilizada com a densidade final da peça. As peças produzidas por FSL mostraram uma elevada densificação (densidade relativa superior a 99,49%) com uma reduzida porosidade homogeneamente dispersa no material. Uma ...
The corrosion resistance of Fe–M–B–Cu alloys in which M is a transition metal of two first series... more The corrosion resistance of Fe–M–B–Cu alloys in which M is a transition metal of two first series, particularly concerning the effect of composition and also concerning the affect of corrosion on magnetic properties have not been evaluated. In this paper, the effect of composition and partial crystallization on corrosion resistance of Fe80Nb3.5Zr3.5B12Cu1, Fe80Nb3.5Mo3.5B12Cu1, Fe80Zr3.5Mo3.5B12Cu1 and Fe80Mo7B12Cu1 amorphous alloys and its
Abstract Highly ordered arrays of TiO 2 nanotubes are being considered as very promising to impro... more Abstract Highly ordered arrays of TiO 2 nanotubes are being considered as very promising to improve the osseointegration of titanium based implants to living tissues. However, this improvement must be accompanied by no drawback in the mechanical properties, which is the case of several surface modification techniques available for biomaterials. Therefore, this work investigated for the first time the effect of the surface modification by TiO 2 nanotubes formation on the fatigue response of Ti-6Al-4V biomedical alloy. Highly organized nanotubes with an average diameter and length respectively of 90 and 600 nm were successfully produced by electrochemical anodization. Based on the standardized staircase method, fatigue tests of the treated specimens were conducted in physiological media at 37 °C, and compared to the untreated polished specimens. The mean and standard deviation values of the fatigue limit calculated through the Dixon-Mood equations were equal for both surface conditions. This result suggests that the employed condition of anodization was satisfactory on growing a nanotubes coating that was not deleterious to the fatigue performance of the alloy, what is a relevant achievement that assures the possibility of having high osseointegration and at the same time keeping the mechanical properties.
The Equal Channel Angular Extrusion in Grade 2 and 4 commercially pure titanium raises the yield ... more The Equal Channel Angular Extrusion in Grade 2 and 4 commercially pure titanium raises the yield strength, ultimate tensile strength, elongation, fatigue limit, besides to attend the requirements of torque and angle of rupture for implants.
A metastable beta TMZF alloy was tested by isothermal compression under different conditions of d... more A metastable beta TMZF alloy was tested by isothermal compression under different conditions of deformation temperature (923 to 1173 K), strain rate (0.172, 1.72, and 17.2 s−1), and a constant strain of 0.8. Stress–strain curves, constitutive constants calculations, and microstructural analysis were performed to understand the alloy’s hot working behavior in regards to the softening and hardening mechanisms operating during deformation. The primary softening mechanism was dynamic recovery, promoting dynamic recrystallization delay during deformation at higher temperatures and low strain rates. Mechanical twinning was an essential deformation mechanism of this alloy, being observed on a nanometric scale. Spinodal decomposition evidence was found to occur during hot deformation. Different models of phenomenological constitutive equations were tested to verify the effectiveness of flow stress prediction. The stress exponent n, derived from the strain-compensated Arrhenius-type constitu...
Resumo: O presente trabalho teve como objetivo a determinação dos parâmetros ótimos do processo d... more Resumo: O presente trabalho teve como objetivo a determinação dos parâmetros ótimos do processo de manufatura aditiva de Fusão Seletiva a Laser (FSL) para o aço 316L visando a obtenção de peças com alta densidade, utilizando equipamento fabricado no Brasil. Foi realizada também uma completa caracterização estrutural tanto da matéria prima utilizada (pó comercial) quanto das peças mais densas obtidas. As propriedades mecânicas das peças produzidas por FSL também foram avaliadas e comparadas com peça fabricada de forma convencional. Foi observado que a densidade das peças aumenta com o aumento da densidade volumétrica de energia fornecida pelo laser até atingir um patamar de máxima densidade. Um modelo polinomial foi proposto correlacionando a densidade volumétrica de energia utilizada com a densidade final da peça. As peças produzidas por FSL mostraram uma elevada densificação (densidade relativa superior a 99,49%) com uma reduzida porosidade homogeneamente dispersa no material. Uma ...
The corrosion resistance of Fe–M–B–Cu alloys in which M is a transition metal of two first series... more The corrosion resistance of Fe–M–B–Cu alloys in which M is a transition metal of two first series, particularly concerning the effect of composition and also concerning the affect of corrosion on magnetic properties have not been evaluated. In this paper, the effect of composition and partial crystallization on corrosion resistance of Fe80Nb3.5Zr3.5B12Cu1, Fe80Nb3.5Mo3.5B12Cu1, Fe80Zr3.5Mo3.5B12Cu1 and Fe80Mo7B12Cu1 amorphous alloys and its
Abstract Highly ordered arrays of TiO 2 nanotubes are being considered as very promising to impro... more Abstract Highly ordered arrays of TiO 2 nanotubes are being considered as very promising to improve the osseointegration of titanium based implants to living tissues. However, this improvement must be accompanied by no drawback in the mechanical properties, which is the case of several surface modification techniques available for biomaterials. Therefore, this work investigated for the first time the effect of the surface modification by TiO 2 nanotubes formation on the fatigue response of Ti-6Al-4V biomedical alloy. Highly organized nanotubes with an average diameter and length respectively of 90 and 600 nm were successfully produced by electrochemical anodization. Based on the standardized staircase method, fatigue tests of the treated specimens were conducted in physiological media at 37 °C, and compared to the untreated polished specimens. The mean and standard deviation values of the fatigue limit calculated through the Dixon-Mood equations were equal for both surface conditions. This result suggests that the employed condition of anodization was satisfactory on growing a nanotubes coating that was not deleterious to the fatigue performance of the alloy, what is a relevant achievement that assures the possibility of having high osseointegration and at the same time keeping the mechanical properties.
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Papers by Claudemiro Bolfarini