Dilermando Travessa - Academia.edu (original) (raw)

Papers by Dilermando Travessa

Research Square (Research Square), Aug 3, 2022

The fatigue life of aged 18Ni300 maraging steel was investigated in two different surface conditi... more The fatigue life of aged 18Ni300 maraging steel was investigated in two different surface conditions: polished and grit-blasted. Axial fatigue tests results, plotted in the form of S-N curves were used to correlate the fatigue performance and the surface characteristics, carefully characterized using a combination of experimental techniques, including Xray diffraction (XRD), contact pro lometry, microhardness testing, scanning electron microscopy (SEM), and stereo optical microscopy (S-OM). The results show that turn-machining of round fatigue samples forms a thin recrystallized layer over the steel surface, which remains after polishing. Roughness increases signi cantly after grit-blasting, but strain hardening and compressive residual stresses developed after blasting outweigh the deleterious increase of roughness and the fatigue life increases in comparison to the polished condition. Both crack initiation and propagation are retarded under the effects of blasting.

Materials Research-ibero-american Journal of Materials, Aug 25, 2016

A structural and mechanical characterization of pure aluminum and 2124 T6 aluminum alloy reinforc... more A structural and mechanical characterization of pure aluminum and 2124 T6 aluminum alloy reinforced with quasicrystalline phases of composition Al 65 Cu 20 Fe 15 and Al 70.5 Pd 21 Mn 8.5 (%at.) were performed. The quasicrystalline phases were synthesized by arc melting and then milled to produce powder of the alloys, which were then mechanical mixed with the starting powders of aluminum and 2124 aluminum alloy. The composites were produced by hot extrusion of a mechanical mixture containing 20% (%wt.) of the reinforcing phases on the metallic matrix. The structural characterization of the composites was carried out by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Mechanical characterization was carried out by Vickers hardness measurements and torsion tests at room temperature. The pure aluminum/quasicrystal composite showed the presence of the same phases from the starting powder mixture while for the 2124 aluminum alloy/Al 65 Cu 20 Fe 15 the quasicrystalline phase transformed to the tetragonal ω-Al 7 Cu 2 Fe during the solution heat treatment. Mechanical strength of the composites presented a substantial increase in comparison to the original matrix metal. While the equivalent ultimate tensile strength of the Al/quasicrystal composites reached values up to 215MPa and Vickers hardness up to 60HV, the 2124/quasicrystal composites reached values up to 670MPa and Vickers hardness up to 190HV.

Social Science Research Network, 2022

The development aluminum matrix composites, using carbon nanotubes as strengthening dispersion ph... more The development aluminum matrix composites, using carbon nanotubes as strengthening dispersion phase, is of great interest for the transport sector, that continuously demands high strength-low density materials for efficient structures.

Metals

In this study, we successfully obtained a 2Mg-Fe mixture through mechanical alloying (MA) and pro... more In this study, we successfully obtained a 2Mg-Fe mixture through mechanical alloying (MA) and processed it via accumulative roll bonding (ARB) (MA+ARB). Our primary focus was to analyze the impact of ambient air exposure while also evaluating the processing route. Some powder samples were exposed to air for 12 months (stored in a glass desiccator with an average yearly temperature and relative humidity of ~27 °C and 50.5%) before undergoing ARB processing. The Mg samples obtained after ARB processing exhibited a (002)-type texture. Our results demonstrate that all samples, including those processed via ARB, could rapidly absorb hydrogen within a matter of minutes despite considerable differences in surface area between powders and rolled samples. Grain size reduction by MA and ARB processing and texturing may have influenced this behavior. ARB-processed samples reached approximately 60% (~1.8 wt.%) of their maximum acquired capacity within just 24 min compared to powders (~2.2 wt.%)...

Transactions of Nonferrous Metals Society of China, 2022

Comprehensive Materials Processing, 2014

The creep age forming process (CAF), also known as the creep forming or age forming process, amon... more The creep age forming process (CAF), also known as the creep forming or age forming process, among other less usual designations ( 1–8 ), is a mechanic-metallurgical forming process applicable to parts manufactured from metallic sheets or plates. It is more suitable for large-contoured parts presenting smooth curvatures ( 9 ), such as aircraft wing skins. Differently from other metal-forming processes that are based on plastic flow, the CAF concept has the advantage of using heat treatment cycles of metals to impose stresses to be released under the effect of temperature and time, by creep mechanisms. CAF simultaneously strengthens the part and changes its shape, resulting in a one-step forming and heat treatment process.

Corrosion Science, Dec 1, 2022

In this study, we successfully obtained a 2Mg-Fe mixture through mechanical alloying (MA) and pro... more In this study, we successfully obtained a 2Mg-Fe mixture through mechanical alloying (MA) and processed it via accumulative roll bonding (ARB) (MA+ARB). Our primary focus was to analyze the impact of ambient air exposure while also evaluating the processing route. Some powder samples were exposed to air for 12 months before undergoing ARB processing. The Mg samples obtained after ARB processing exhibited a (002)-type texture. Our results demonstrate that all samples, including those processed via ARB, could rapidly absorb hydrogen within a matter of minutes, despite considerable differences in surface area between powders and rolled samples. ARB-processed samples reached approximately 60% of their maximum acquired capacity within just 24 minutes, compared to powders stored for a year which took 36 minutes. Also, the desorption temperatures were lower than those of MgH2. The absorption and desorption kinetics remained fast even after prolonged exposure to air. Although there were min...

Materials Research-Ibero-American Journal of Materials, 2012

Surface and Coatings Technology

Abstract Carbon nanotubes (CNTs) could be an excellent reinforcement for metal matrix composites,... more Abstract Carbon nanotubes (CNTs) could be an excellent reinforcement for metal matrix composites, specifically for composites with aluminum or aluminum alloy matrix. Surface modification to improve hardness and other material properties has been performed by laser surface melting (LSM) process, where the laser beam melts the substrate together with alloying elements or reinforcing phase additives. In this work, Multiwalled CNTs (MWCNTs) were mixed by the electrostatic adsorption process with aluminum powder and the resulting mixed powder was laser melted on the surface of a 6061-aluminum alloy substrate. As a result, a modified substrate surface has been obtained from the Al/MWCNT – substrate co-melting, dilution and re-solidification processes. This modified layer was obtained by different LSM parameters and were characterized by Optical (OM) and Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), Field Emission Gun Scanning Electron Microscopy (FEG-SEM), X-Ray Diffraction (XRD) and Raman Spectroscopy (RS). The resulting mechanical behavior was evaluated by Vickers microhardness tests. The results showed that the presence of MWCNT in the aluminum powder improves the laser energy absorption, leading to the formation of a deeper modified layer, with segregation of Si particles homogeneously dispersed and improving the hardness. The formation of Al4C3 was not observed, evidencing that the MWCNTs did not react with the molten Al matrix during the LSM process.

Journal of Electronic Materials

In this work, the commercial age-hardenable Cu-0.81Cr-0.07Zr alloy was solution heat treated at 9... more In this work, the commercial age-hardenable Cu-0.81Cr-0.07Zr alloy was solution heat treated at 930°C and 1020°C and processed at room temperature by 1 and 4 equal-channel angular pressing (ECAP) passes through routes A and BC. Aging treatments were performed in the ECAPed and as-solubilized samples. The effects of processing and heat treatments on hardness and electrical conductivity were analyzed and correlated with microstructural evolution. It was found that during ECAP, grain refinement and dislocation hardening were the predominant hardening mechanisms. The electrical conductivity was mainly affected by the amount of solute in solid solution, being practically unaffected by the deformation caused by ECAP. It was observed that the precipitation kinetics were accelerated in the samples processed by ECAP, resulting in a decrease in the peak aging temperature. After 4 passes of ECAP followed by aging, the samples reached peak hardness of 193 HV and 201 HV for samples solubilized at 930°C and 1020°C, respectively. These values correspond to a 13% and 18% increase in hardness compared to commercial Cu-Cr-Zr alloys produced by a conventional solution heat treatment/cold working-aging route. Furthermore, the electrical conductivity remained above 70% IACS after ECAP-aging, which is still very attractive for electrical applications.

Journal of Alloys and Compounds

Journal of Alloys and Compounds

Abstract Aluminum and aluminum alloys have been very useful in the industry, mainly in the transp... more Abstract Aluminum and aluminum alloys have been very useful in the industry, mainly in the transport sector. So, is important to improve their mechanical properties to increase their applications. Carbon nanotubes (CNTs) could be an excellent reinforcing phase for metal matrix composites, specifically for composites with aluminum or aluminum alloy matrix. However, CNTs dispersion, wettability, and interaction with the matrix must be improved, without damaging their structure. In this work, multi-walled CNTs (MWCNTs) were coated by the sol-gel process with a titanium oxide (TiO2) layer with three different thickness and calcined at two different temperatures: 500 °C and 750 °C. The resultant powder was mixed by electrostatic adsorption method with aluminum powder and cold compacted. To simulate high temperature processing, the compacted disks were pressureless heated at 850 °C, aiming to check the effect of TiO2 in protecting the MWCNT when in contact with melted Al. The TiO2 coated MWCNT samples were characterized by a range of analytical techniques including Field-Emission Gun Scanning Electron Microscopy (FEG-SEM), X-ray diffraction (XRD), Z-Potential, Brunauer–Emmett–Teller (BET), Energy Dispersive X-Ray Spectroscopy (EDS) and Raman Spectroscopy (RS). The effect of the TiO2 layer as a protective barrier on the MWCNT against the Al4C3 formation during the heating process and the hardness of the Al/MWCNT (coated and uncoated) composite were studied. The results show that the MWCNT were successful coverage by a uniform amorphous TiO2 layer. After calcination at 500 °C and 750 °C, the layer was completely crystallized into a TiO2 film, with reduced surface area and pore volume. Electrostatic adsorption between TiO2 covered MWCNT and Al powders in aqueous suspension was found to disperse the reinforcing phase prior to consolidation. On the heat-treated discs, the formation of Al4C3 phase was observed to occur only for uncoated MWCNT samples, showing that the TiO2 layer effectively protected the nanotubes in presence of melted Al. The microhardness of the heated samples was increased up to 26% when reinforced with MWCNT and up to 46% when reinforced with TiO2 coated MWCNT, compared with pure aluminum.

Surface and Coatings Technology

ABM Proceedings

High strength-light weight materials are very attractive for the transportation sector, particula... more High strength-light weight materials are very attractive for the transportation sector, particularly to the aerospace industry. High strength-age hardenable aluminium alloys are widely used in airframes due to their unique combination of strength, density, toughness, corrosion resistance, cost and easy processing. However, the hardening capacity of such alloys is somehow saturated due to thermodynamic issues related to the conventional processing. The production of aluminum-matrix composites is a promising strategy to overcome this limitation, resulting in strength levels that cannot be reached by actual commercial aluminum alloys. In the present work, multiwall carbon nanotubes were used to reinforce the AA6061 aluminium alloy. 1 and 2% weight percent of MWCNT were mixed to the alloy powder by highenergy ball-milling process. The blended powder was consolidated by hot extrusion. The obtained composite bars were submitted to heat treatment for the T6 condition in order to combine both CNT dispersion and precipitation hardening effects. Optical and scanning electron microscopy, as well as hardeness testing, was used to characterize the bars. Typical wrought microstructure, free of defects, was observed on the extruded bars. Hardness of the composites was observed to increase by 20, 28 and 68% for 1% MWCNT 6 h milling, 2% MWCNT 6 h milling and 2% MWCNT 10 h milling, respectively, in the as-extruded condition. The better performance for the composites blended at higher milling time was attributed to a better nanotubes dispersion. Subsequent heat treatment to the T6 condition did not result in additional hardening.

Journal of Alloys and Compounds

Journal of Manufacturing Science and Engineering

This study compares two processing routes, Selective Laser Melting (SLM) and Flame Spray (FS) to ... more This study compares two processing routes, Selective Laser Melting (SLM) and Flame Spray (FS) to fabricate an Al/MWCNT composite layer over an aluminum alloy 6013 (AA6013) substrate. The final surface and cross-sections morphologies were evaluated by Scanning Electron Microscopy (SEM) and Optical Microscopy (OM). The effect of these processing routes on the multiwall carbon nanotubes (MWCNT) was evaluated by X-ray diffraction (XRD) and Raman spectroscopy (RS). Finally, the mechanical properties were evaluated by Vickers microhardness. The Raman bands corresponding to carbon were identified in the spectrum of both samples processed by SLM and FS. However, in the latter was also identified the Al4C3 formation. The Vickers microhardness results show an increase in the hardness values of the FS and SLM processed coatings of 44% and 9%, respectively, when compared to the AA6013 substrate.

Key Engineering Materials

Ti alloys have been intensely used for human implants due to its excellent characteristics, like ... more Ti alloys have been intensely used for human implants due to its excellent characteristics, like bio-inertness, low density, and corrosion resistance. However, some alloying elements were found to be toxic for the human body, which restricts the use of some alloys. Furthermore, there are two additional and essential aspects to be considered. The first relates to the young modulus that, despite being lower than other alloys commonly used for this purpose, it is still far over from the human bone modulus. Such high modulus can result in the stress shield phenomena and the consequent implant losing. The second aspect relates to the fact that bio-inertness does not guarantee a complete tissue integration to the implant and, consequently, the expected implant performance. In this context, new low modulus b-Ti alloys containing nontoxic elements have been developed in recent years, and several surface modification processes have been proposed to promote better implant/tissue integration.I...

Research Square (Research Square), Aug 3, 2022

The fatigue life of aged 18Ni300 maraging steel was investigated in two different surface conditi... more The fatigue life of aged 18Ni300 maraging steel was investigated in two different surface conditions: polished and grit-blasted. Axial fatigue tests results, plotted in the form of S-N curves were used to correlate the fatigue performance and the surface characteristics, carefully characterized using a combination of experimental techniques, including Xray diffraction (XRD), contact pro lometry, microhardness testing, scanning electron microscopy (SEM), and stereo optical microscopy (S-OM). The results show that turn-machining of round fatigue samples forms a thin recrystallized layer over the steel surface, which remains after polishing. Roughness increases signi cantly after grit-blasting, but strain hardening and compressive residual stresses developed after blasting outweigh the deleterious increase of roughness and the fatigue life increases in comparison to the polished condition. Both crack initiation and propagation are retarded under the effects of blasting.

Materials Research-ibero-american Journal of Materials, Aug 25, 2016

A structural and mechanical characterization of pure aluminum and 2124 T6 aluminum alloy reinforc... more A structural and mechanical characterization of pure aluminum and 2124 T6 aluminum alloy reinforced with quasicrystalline phases of composition Al 65 Cu 20 Fe 15 and Al 70.5 Pd 21 Mn 8.5 (%at.) were performed. The quasicrystalline phases were synthesized by arc melting and then milled to produce powder of the alloys, which were then mechanical mixed with the starting powders of aluminum and 2124 aluminum alloy. The composites were produced by hot extrusion of a mechanical mixture containing 20% (%wt.) of the reinforcing phases on the metallic matrix. The structural characterization of the composites was carried out by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Mechanical characterization was carried out by Vickers hardness measurements and torsion tests at room temperature. The pure aluminum/quasicrystal composite showed the presence of the same phases from the starting powder mixture while for the 2124 aluminum alloy/Al 65 Cu 20 Fe 15 the quasicrystalline phase transformed to the tetragonal ω-Al 7 Cu 2 Fe during the solution heat treatment. Mechanical strength of the composites presented a substantial increase in comparison to the original matrix metal. While the equivalent ultimate tensile strength of the Al/quasicrystal composites reached values up to 215MPa and Vickers hardness up to 60HV, the 2124/quasicrystal composites reached values up to 670MPa and Vickers hardness up to 190HV.

Social Science Research Network, 2022

The development aluminum matrix composites, using carbon nanotubes as strengthening dispersion ph... more The development aluminum matrix composites, using carbon nanotubes as strengthening dispersion phase, is of great interest for the transport sector, that continuously demands high strength-low density materials for efficient structures.

Metals

In this study, we successfully obtained a 2Mg-Fe mixture through mechanical alloying (MA) and pro... more In this study, we successfully obtained a 2Mg-Fe mixture through mechanical alloying (MA) and processed it via accumulative roll bonding (ARB) (MA+ARB). Our primary focus was to analyze the impact of ambient air exposure while also evaluating the processing route. Some powder samples were exposed to air for 12 months (stored in a glass desiccator with an average yearly temperature and relative humidity of ~27 °C and 50.5%) before undergoing ARB processing. The Mg samples obtained after ARB processing exhibited a (002)-type texture. Our results demonstrate that all samples, including those processed via ARB, could rapidly absorb hydrogen within a matter of minutes despite considerable differences in surface area between powders and rolled samples. Grain size reduction by MA and ARB processing and texturing may have influenced this behavior. ARB-processed samples reached approximately 60% (~1.8 wt.%) of their maximum acquired capacity within just 24 min compared to powders (~2.2 wt.%)...

Transactions of Nonferrous Metals Society of China, 2022

Comprehensive Materials Processing, 2014

The creep age forming process (CAF), also known as the creep forming or age forming process, amon... more The creep age forming process (CAF), also known as the creep forming or age forming process, among other less usual designations ( 1–8 ), is a mechanic-metallurgical forming process applicable to parts manufactured from metallic sheets or plates. It is more suitable for large-contoured parts presenting smooth curvatures ( 9 ), such as aircraft wing skins. Differently from other metal-forming processes that are based on plastic flow, the CAF concept has the advantage of using heat treatment cycles of metals to impose stresses to be released under the effect of temperature and time, by creep mechanisms. CAF simultaneously strengthens the part and changes its shape, resulting in a one-step forming and heat treatment process.

Corrosion Science, Dec 1, 2022

In this study, we successfully obtained a 2Mg-Fe mixture through mechanical alloying (MA) and pro... more In this study, we successfully obtained a 2Mg-Fe mixture through mechanical alloying (MA) and processed it via accumulative roll bonding (ARB) (MA+ARB). Our primary focus was to analyze the impact of ambient air exposure while also evaluating the processing route. Some powder samples were exposed to air for 12 months before undergoing ARB processing. The Mg samples obtained after ARB processing exhibited a (002)-type texture. Our results demonstrate that all samples, including those processed via ARB, could rapidly absorb hydrogen within a matter of minutes, despite considerable differences in surface area between powders and rolled samples. ARB-processed samples reached approximately 60% of their maximum acquired capacity within just 24 minutes, compared to powders stored for a year which took 36 minutes. Also, the desorption temperatures were lower than those of MgH2. The absorption and desorption kinetics remained fast even after prolonged exposure to air. Although there were min...

Materials Research-Ibero-American Journal of Materials, 2012

Surface and Coatings Technology

Abstract Carbon nanotubes (CNTs) could be an excellent reinforcement for metal matrix composites,... more Abstract Carbon nanotubes (CNTs) could be an excellent reinforcement for metal matrix composites, specifically for composites with aluminum or aluminum alloy matrix. Surface modification to improve hardness and other material properties has been performed by laser surface melting (LSM) process, where the laser beam melts the substrate together with alloying elements or reinforcing phase additives. In this work, Multiwalled CNTs (MWCNTs) were mixed by the electrostatic adsorption process with aluminum powder and the resulting mixed powder was laser melted on the surface of a 6061-aluminum alloy substrate. As a result, a modified substrate surface has been obtained from the Al/MWCNT – substrate co-melting, dilution and re-solidification processes. This modified layer was obtained by different LSM parameters and were characterized by Optical (OM) and Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), Field Emission Gun Scanning Electron Microscopy (FEG-SEM), X-Ray Diffraction (XRD) and Raman Spectroscopy (RS). The resulting mechanical behavior was evaluated by Vickers microhardness tests. The results showed that the presence of MWCNT in the aluminum powder improves the laser energy absorption, leading to the formation of a deeper modified layer, with segregation of Si particles homogeneously dispersed and improving the hardness. The formation of Al4C3 was not observed, evidencing that the MWCNTs did not react with the molten Al matrix during the LSM process.

Journal of Electronic Materials

In this work, the commercial age-hardenable Cu-0.81Cr-0.07Zr alloy was solution heat treated at 9... more In this work, the commercial age-hardenable Cu-0.81Cr-0.07Zr alloy was solution heat treated at 930°C and 1020°C and processed at room temperature by 1 and 4 equal-channel angular pressing (ECAP) passes through routes A and BC. Aging treatments were performed in the ECAPed and as-solubilized samples. The effects of processing and heat treatments on hardness and electrical conductivity were analyzed and correlated with microstructural evolution. It was found that during ECAP, grain refinement and dislocation hardening were the predominant hardening mechanisms. The electrical conductivity was mainly affected by the amount of solute in solid solution, being practically unaffected by the deformation caused by ECAP. It was observed that the precipitation kinetics were accelerated in the samples processed by ECAP, resulting in a decrease in the peak aging temperature. After 4 passes of ECAP followed by aging, the samples reached peak hardness of 193 HV and 201 HV for samples solubilized at 930°C and 1020°C, respectively. These values correspond to a 13% and 18% increase in hardness compared to commercial Cu-Cr-Zr alloys produced by a conventional solution heat treatment/cold working-aging route. Furthermore, the electrical conductivity remained above 70% IACS after ECAP-aging, which is still very attractive for electrical applications.

Journal of Alloys and Compounds

Journal of Alloys and Compounds

Abstract Aluminum and aluminum alloys have been very useful in the industry, mainly in the transp... more Abstract Aluminum and aluminum alloys have been very useful in the industry, mainly in the transport sector. So, is important to improve their mechanical properties to increase their applications. Carbon nanotubes (CNTs) could be an excellent reinforcing phase for metal matrix composites, specifically for composites with aluminum or aluminum alloy matrix. However, CNTs dispersion, wettability, and interaction with the matrix must be improved, without damaging their structure. In this work, multi-walled CNTs (MWCNTs) were coated by the sol-gel process with a titanium oxide (TiO2) layer with three different thickness and calcined at two different temperatures: 500 °C and 750 °C. The resultant powder was mixed by electrostatic adsorption method with aluminum powder and cold compacted. To simulate high temperature processing, the compacted disks were pressureless heated at 850 °C, aiming to check the effect of TiO2 in protecting the MWCNT when in contact with melted Al. The TiO2 coated MWCNT samples were characterized by a range of analytical techniques including Field-Emission Gun Scanning Electron Microscopy (FEG-SEM), X-ray diffraction (XRD), Z-Potential, Brunauer–Emmett–Teller (BET), Energy Dispersive X-Ray Spectroscopy (EDS) and Raman Spectroscopy (RS). The effect of the TiO2 layer as a protective barrier on the MWCNT against the Al4C3 formation during the heating process and the hardness of the Al/MWCNT (coated and uncoated) composite were studied. The results show that the MWCNT were successful coverage by a uniform amorphous TiO2 layer. After calcination at 500 °C and 750 °C, the layer was completely crystallized into a TiO2 film, with reduced surface area and pore volume. Electrostatic adsorption between TiO2 covered MWCNT and Al powders in aqueous suspension was found to disperse the reinforcing phase prior to consolidation. On the heat-treated discs, the formation of Al4C3 phase was observed to occur only for uncoated MWCNT samples, showing that the TiO2 layer effectively protected the nanotubes in presence of melted Al. The microhardness of the heated samples was increased up to 26% when reinforced with MWCNT and up to 46% when reinforced with TiO2 coated MWCNT, compared with pure aluminum.

Surface and Coatings Technology

ABM Proceedings

High strength-light weight materials are very attractive for the transportation sector, particula... more High strength-light weight materials are very attractive for the transportation sector, particularly to the aerospace industry. High strength-age hardenable aluminium alloys are widely used in airframes due to their unique combination of strength, density, toughness, corrosion resistance, cost and easy processing. However, the hardening capacity of such alloys is somehow saturated due to thermodynamic issues related to the conventional processing. The production of aluminum-matrix composites is a promising strategy to overcome this limitation, resulting in strength levels that cannot be reached by actual commercial aluminum alloys. In the present work, multiwall carbon nanotubes were used to reinforce the AA6061 aluminium alloy. 1 and 2% weight percent of MWCNT were mixed to the alloy powder by highenergy ball-milling process. The blended powder was consolidated by hot extrusion. The obtained composite bars were submitted to heat treatment for the T6 condition in order to combine both CNT dispersion and precipitation hardening effects. Optical and scanning electron microscopy, as well as hardeness testing, was used to characterize the bars. Typical wrought microstructure, free of defects, was observed on the extruded bars. Hardness of the composites was observed to increase by 20, 28 and 68% for 1% MWCNT 6 h milling, 2% MWCNT 6 h milling and 2% MWCNT 10 h milling, respectively, in the as-extruded condition. The better performance for the composites blended at higher milling time was attributed to a better nanotubes dispersion. Subsequent heat treatment to the T6 condition did not result in additional hardening.

Journal of Alloys and Compounds

Journal of Manufacturing Science and Engineering

This study compares two processing routes, Selective Laser Melting (SLM) and Flame Spray (FS) to ... more This study compares two processing routes, Selective Laser Melting (SLM) and Flame Spray (FS) to fabricate an Al/MWCNT composite layer over an aluminum alloy 6013 (AA6013) substrate. The final surface and cross-sections morphologies were evaluated by Scanning Electron Microscopy (SEM) and Optical Microscopy (OM). The effect of these processing routes on the multiwall carbon nanotubes (MWCNT) was evaluated by X-ray diffraction (XRD) and Raman spectroscopy (RS). Finally, the mechanical properties were evaluated by Vickers microhardness. The Raman bands corresponding to carbon were identified in the spectrum of both samples processed by SLM and FS. However, in the latter was also identified the Al4C3 formation. The Vickers microhardness results show an increase in the hardness values of the FS and SLM processed coatings of 44% and 9%, respectively, when compared to the AA6013 substrate.

Key Engineering Materials

Ti alloys have been intensely used for human implants due to its excellent characteristics, like ... more Ti alloys have been intensely used for human implants due to its excellent characteristics, like bio-inertness, low density, and corrosion resistance. However, some alloying elements were found to be toxic for the human body, which restricts the use of some alloys. Furthermore, there are two additional and essential aspects to be considered. The first relates to the young modulus that, despite being lower than other alloys commonly used for this purpose, it is still far over from the human bone modulus. Such high modulus can result in the stress shield phenomena and the consequent implant losing. The second aspect relates to the fact that bio-inertness does not guarantee a complete tissue integration to the implant and, consequently, the expected implant performance. In this context, new low modulus b-Ti alloys containing nontoxic elements have been developed in recent years, and several surface modification processes have been proposed to promote better implant/tissue integration.I...