Showing papers on "Alloy published in 2008"
TL;DR: The results of tensile tests and in vitro corrosion tests indicated that Mg-1Ca alloy had the acceptable biocompatibility as a new kind of biodegradable implant material and a solid alloy/liquid solution interface model was proposed to interpret the biocorrosion process and the associated hydroxyapatite mineralization.
1,385 citations
TL;DR: In this article, vanadium-and aluminum-free alloys have been introduced for implant applications, which are considered to be the most attractive metallic materials for biomedical applications, but vanadium can have a possible toxic effect resulting from released vanadium and aluminum.
Abstract: Titanium alloys are considered to be the most attractive metallic materials for biomedical applications. Ti-6Al-4V has long been favored for biomedical applications. However, for permanent implant applications the alloy has a possible toxic effect resulting from released vanadium and aluminum. For this reason, vanadium-and aluminum-free alloys have been introduced for implant applications.
798 citations
TL;DR: In this article, the basic concepts of advanced high strength steels (AHSS) for use in the automobile industry, including chemical composition design, microstructure and mechanical properties development during thermomechanical processing, production technology characterisation, potential applications and performance in service, are presented.
648 citations
TL;DR: The in vitro study suggests that calcium-containing magnesium alloys to be a promising candidate for their applications in degradable orthopaedic implants, and it is worthwhile to further investigate the in vivo corrosion behaviour of these alloys.
484 citations
15 Sep 2008-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, an AlCrFeCoNi high entropy alloy was prepared by vacuum arc melting and only diffraction peak corresponding to a BCC crystal structure was observed for this AlCr FeCoNiHigh Entropy Alloy.
Abstract: An AlCrFeCoNi high entropy alloy was prepared by vacuum arc melting. Only diffraction peak corresponding to a BCC crystal structure is observed for this AlCrFeCoNi high entropy alloy. The microstructure of this AlCrFeCoNi alloy is polygonal grains with intragranular dendritic segregation. Dendritic segregation area is found to be Al, Ni rich and Cr, Fe deplete, while interdendritic segregation area is Cr, Fe rich and Al, Ni deplete. The distribution of Co is essentially identical. The fine microstructure of dendritic segregation area and of interdendritic segregation area is found to be nanoscale spherical precipitates morphology and basket-weave morphology, respectively. Results of EDS attached on high resolution scanning electron microscope (SEM) revealed that these morphological characteristics are also resulted from elements segregation. This AlCrFeCoNi high entropy alloy exhibits excellent compressive properties. The yield stress, compressive strength and plastic strain of the alloy reaches 1250.96, 2004.23 MPa, and 32.7%, respectively. The fracture mechanism of this AlCrFeCoNi high entropy alloy is observed as cleavage fracture and slip separation.
399 citations
TL;DR: In this paper, the potentiodynamic polarization and electrochemical impedance spectroscopy of the Al x CrFe 1.5 MnNi 0.5 alloys, obtained in H 2 SO 4 and NaCl solutions, clearly revealed that the corrosion resistance increases as the concentration of aluminium decreases.
316 citations
15 Dec 2008-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, as-cast Mg-Zn-Mn-Ca alloys were investigated for biomedical application in detail by optical microscopy, scanning electronic microscopy (SEM), mechanical properties testing and electrochemical measurement.
Abstract: Microstructure, mechanical properties and bio-corrosion properties of as-cast Mg–Zn–Mn–Ca alloys were investigated for biomedical application in detail by optical microscopy, scanning electronic microscopy (SEM), mechanical properties testing and electrochemical measurement. SEM and optical microscopy observation indicated that the grain size of the as-cast alloys significantly decreased with the increasing of Ca content up to 0.5 wt.%. Further increasing of Ca content did not refine the grain more. The phase constitute was mainly controlled by the atomic ratio of Zn to Ca. When the ratio was more than 1.0–1.2, the alloy was mainly composed of primary Mg and lamellar eutectic (α-Mg + Ca 2 Mg 6 Zn 3 ), while the alloy was composed of primary Mg and divorced eutectic (α-Mg + Mg 2 Ca + Ca 2 Mg 6 Zn 3 ) when the atomic ratio was less than 1.0–1.2. The yield strength of the as-cast alloy increased but the elongation and the tensile strength increased first and then decreased with the increasing of Ca content. It was thought that Mg 2 Ca phase deteriorated the tensile strength and ductility. Electrochemical measurements indicated that Mg 2 Ca phase improved the corrosion resistance of the as-cast alloy.
300 citations
TL;DR: In this paper, the aluminum alloys AA5083 and AA1100 were tested in seawater at 23 and 60 °C and the results showed that the type of intermetallic particles in the aluminum alloy played a major role in passivity breakdown and pit morphology.
289 citations
TL;DR: The Fe35Mn alloy was found to be essentially austenitic with fine MnO particles aligned along the rolling direction, and it exhibits antiferromagnetic behaviour and its magnetic susceptibility is not altered by plastic deformation, providing an excellent MRI compatibility.
Abstract: An Fe–35 wt-%Mn alloy, aimed to be used as a metallic degradable biomaterial for stent applications, was prepared via a powder metallurgy route. The effects of processing conditions on the microstructure, mechanical properties, magnetic susceptibility and corrosion behaviour were investigated and the results were compared to those of the SS316L alloy, a gold standard for stent applications. The Fe35Mn alloy was found to be essentially austenitic with fine MnO particles aligned along the rolling direction. The alloy is ductile with a strength approaching that of wrought SS316L. It exhibits antiferromagnetic behaviour and its magnetic susceptibility is not altered by plastic deformation, providing an excellent MRI compatibility. Its corrosion rate was evaluated in a modified Hank's solution, and found superior to that of pure iron (slow in vivo degradation rate). In conclusion, the mechanical, magnetic and corrosion characteristics of the Fe35Mn alloy are considered suitable for further development ...
282 citations
TL;DR: The enhanced specific ORR activity of acid-treated "Pt3Co" nanoparticles can be related to composition variations at the atomic scale and the formation of percolated Pt-rich and Pt-poor regions within individual particles.
Abstract: Atomically resolved structures and compositions of Pt alloy nanoparticles were obtained using aberration-corrected high-angle dark field imaging, which was correlated to specific ORR activity based on a Pt surface area. The enhanced specific ORR activity (∼2 times relative to Pt) of acid-treated “Pt3Co” nanoparticles can be related to composition variations at the atomic scale and the formation of percolated Pt-rich and Pt-poor regions within individual particles. Upon annealing, we show direct evidence of surface Pt sandwich-segregation structures, which correspond to a specific ORR activity ∼4 times relative to Pt.
275 citations
TL;DR: In this article, the corrosion performance of WE43-T6 and AZ91D magnesium alloys with and without treatment by plasma electrolytic oxidation (PEO) was investigated by electrochemical measurements in 3.5-wt. NaCl solution.
TL;DR: The hydrogen evolution reaction on the electrodeposited Ni-Mo alloy coatings, as well as their electrochemical properties in the NaOH solutions, have been investigated by the polarization measurements, cyclic voltammetry and EIS technique.
TL;DR: In this article, the deformation behavior of wrought magnesium alloys is discussed in light of key metallurgical features such as alloy composition, grain size, and work hardening rate.
Abstract: The use of magnesium alloys in structural applications has great potential for the lightweighting of transportation vehicles. Research within the CAST Cooperative Research Centre has tackled some of the important issues related to the use of magnesium in structural applications. To this end, a new alloy with extrudability and properties similar to 6000 series aluminum alloys has been developed. Furthermore, a method of laser heating magnesium alloys before self-piercing riveting has enabled high-integrity joining between magnesium components or between magnesium and dissimilar metals. In this paper, new technologies and improved understanding of the deformation behavior of wrought magnesium alloys are discussed in light of key metallurgical features such as alloy composition, grain size, and work hardening rate.
TL;DR: In this article, a cyclic voltammogram of NiCu alloy demonstrates the formation of β/β crystallographic forms of the nickel oxyhydroxide under prolonged repetitive potential cycling in alkaline solution.
TL;DR: In this paper, a sol-gel-based anticorrosion film for AZ31B magnesium alloy was developed and studied based on copolymerization of epoxy-siloxane and titanium or zirconium alkoxides, and tris(trimethylsilyl) phosphate was also used as additive to confer additional corrosion protection.
TL;DR: In this article, the influence of stacking-fault energy (SFE) on microstructural development when processing using high-pressure torsion (HPT) was evaluated using transmission electron microscopy, X-ray diffraction and hardness measurements.
TL;DR: In this article, a new biomedical magnesium-based alloy, i.e., magnesium-calcium (Mg-Ca), has been designed from biological and metallurgical viewpoints, and the microstructure, mechanical and corrosion behaviors of Mg-C alloys with varying calcium content were investigated.
TL;DR: In this paper, the microstructural and mechanical properties of the friction stir welding (FSW) of 1060 aluminum alloy to a commercially pure copper were investigated. And the effect of formation of hard and brittle intermetallic phase at the interface of the joints on the shear strength of the joint was discussed.
TL;DR: In this paper, the extruded alloy consists of coarse and fine-grains with a basal texture, which gives rise to the high tension to compression ratio of 0.9, and the fine microstructure is attributed to the dynamic recrystallization and precipitation that occur during the extrusion.
TL;DR: In this paper, the surface of AM50 magnesium alloy using four different electrolytes containing 10.5% each of K 3PO4 and Na3PO4 in combination with either potassium or sodium hydroxides was analyzed using scanning electron microscopy and X-ray diffraction.
Abstract: In this work coatings were developed on the surface of AM50 magnesium alloy using four different electrolytes containing 10 wt.% each of K3PO4 and Na3PO4 in combination with either potassium or sodium hydroxides. Electrolyte conductivity and breakdown voltage were measured in order to correlate the property of the coating to the nature of electrolyte. Further, the coatings were examined using scanning electron microscopy for surface morphology and cross sectional investigation, X-ray diffraction for phase determination, and electrochemical impedance spectroscopy for corrosion resistance evaluation. The effect of employing different ions in the electrolytes results in different surface morphologies, chemical phases and, consequently, the corrosion resistance of the coatings. The EIS results indicate the presence of porous and compact layers in the structure of the PEO coatings, whilst the overall coating resistance mainly results from the compact layer, the role of the porous layer as a barrier against corrosion is negligible. Finally, a correlation between the passive current density of the bare alloy and the corrosion resistance of the PEO coating is proposed.
TL;DR: In this paper, the authors present results for corrosion potentials, pitting potentials and electrochemical characteristics for intermetallic particles commonly present in high strength aluminum-based alloys, for tests conducted in a 01 M NaCl solution of varying pH via the use of a microcapillary electrochemical cell.
Abstract: This paper presents results for corrosion potentials, pitting potentials, and electrochemical characteristics for intermetallic particles commonly present in high strength aluminum-based alloys, for tests conducted in a 01 M NaCl solution of varying pH via the use of a microcapillary electrochemical cell The intermetallics investigated were Mg2Si, MgZn2 ,A l7Cu2Fe, Al2Cu, Al2CuMg, and Al3Fe Elaboration of the results reveals that the electrochemical behavior of such compounds varies markedly with pH, with attendant ramifications for localized corrosion and protection in Al alloys Examples of this are shown for AA7075-T651, where it is shown that the localized corrosion morphology is drastically different upon the bulk alloy depending on the pH of the test environment A stochastic pitting is observed at an acid pH, near-neutral conditions result in a deterministic-type pitting, and a general corrosion is observed at an alkaline pH
TL;DR: In this article, the influence of two novel aging treatments, T6I6 (130 °C, 80 min + 65 °C) and high-temperature pre-precipitation (HTPP) aging, on the tensile properties, intergranular corrosion, exfoliation corrosion behaviors and microstructures of 7075 Al alloy was studied, which were compared with the T6, T73 and RRA treatments.
01 Sep 2008
TL;DR: In this paper, β-type Ti alloy with a low elastic modulus has proved to be effective for inhibiting bone absorption and enhancing bone remodeling, and simple bioactive surface modifications such as alkali treatment processes and the calcium phosphate glass-ceramic dip-coating method are applicable to newly developed β type Ti alloys such as low-modulus Ti-29Nb-13Ta-4.6Zr.
Abstract: Ti alloys composed of nontoxic and allergy-free elements and Ni-free stainless steels and Co-Cr alloys are currently being developed. Ni-free Ti alloys exhibiting superelastic behavior, or the shape memory effect, are also being developed. β-type Ti alloy with a low elastic modulus has proved to be effective for inhibiting bone absorption and enhancing bone remodeling. Simple bioactive surface modifications such as alkali-treatment processes and the calcium phosphate glass-ceramic dip-coating method are applicable to newly developed β-type Ti alloys such as lowmodulus Ti-29Nb-13Ta-4.6Zr. Blood-compatible polymers such as poly(ethylene glycol) have been successfully fixed on the surface of Ti via chemical bonding by an electrodeposition method. Ti alloys for dental applications have also been recently developed.
TL;DR: In this article, the diffusion-bonding of Mg-Al without and with Zn alloy interlayer has been investigated and it was shown that the addition of Zn Alloy interlayer improves the microstructure of the Mg -Al joints.
TL;DR: In this paper, high-Cr ferritic model steels containing various additions of the refractory elements Nb and/or W were studied with respect to oxidation behaviour (hot) tensile properties, creep behaviour and high-temperature electrical conductivity of the surface oxide scales.
TL;DR: It is suggested that the Ti–40Zr alloy has better mechanical properties, excellent elastic recovery capability and improved grindability at low grinding speed, and has a great potential for use as a dental machining alloy.
Abstract: Structure, mechanical properties and grindability of a series of binary Ti–Zr alloys with zirconium contents ranging from 10 to 40 wt% have been investigated. Commercially pure titanium (c.p. Ti) was used as a control. Experimental results indicated that the diffraction peaks of all the Ti–Zr alloys matched those for α Ti. No β-phase peaks were found. The hardness of the Ti–Zr alloys increased as the Zr contents increased, and ranged from 266 HV (Ti–10Zr) to 350 HV (Ti–40Zr). As the concentration of zirconium in the alloys increased, the strength, elastic recovery angles and hardness increased. Moreover, the elastically recoverable angle of Ti–40Zr was higher than of c.p. Ti by as much as 550%. The grindability of each metal was found to be largely dependent on the grinding conditions. The Ti–40Zr alloy had a higher grinding rate and grinding ratio than c.p. Ti at low speed. The grinding rate of the Ti–40Zr alloy at 500 m/min was about 1.8 times larger than that of c.p. Ti, and the grinding ratio was about 1.6 times larger than that of c.p. Ti. Our research suggested that the Ti–40Zr alloy has better mechanical properties, excellent elastic recovery capability and improved grindability at low grinding speed. The Ti–40Zr alloy has a great potential for use as a dental machining alloy.
TL;DR: In this paper, the dry sliding wear behaviour of unreinforced alloy and composites are studied using Pin-On-Disc machine at a load of 10, 20, 50, 65 and 80 N at a constant sliding velocity of 1 m/s.
20 Dec 2008-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the effects of these added elements on microstructure and properties of AlCrFeCoNiNiCu high entropy alloy were studied and the results indicate that the AlCr FeCoNiCuMn alloy shows almost the same microstructures as in AlCrCoNiCNiCu alloy except for a long-strip Cr-enriched phase.
Abstract: Mn, Ti and V were added in an equal-molar ratio to the AlCrFeCoNiCu alloy and the effects of these added elements on microstructure and properties of AlCrFeCoNiCu high entropy alloy were studied. The results indicate that the AlCrFeCoNiCuMn alloy shows almost the same microstructure as in AlCrFeCoNiCu alloy except for a long-strip Cr-enriched phase. The additions of Ti change the AlCrFeCoNiCu alloy from a dendrite structure to eutectic-cell one. Hence two phases in the eutectic cells are detected as one Al, Ti, Co, Ni enriched phase and another Cr, Fe enriched phase. V added alloy is also a dendrite structure, but V additions change the morphology of dendritic area from modulated plates to ellipsoidal particles. The addition of V into the AlCrFeCoNiCu alloy shows the best strengthening effect and the lowest decrease in the ultimate strain in our experiments.
TL;DR: After 48–96 h immersion, the corrosion reaction and the precipitation reaction reach a stable stage, displaying that the phosphate layer on magnesium surface, especially Zn-containing phosphate layer could provide effective protection for magnesium alloy.
Abstract: The corrosion behaviour of Mg-Mn and Mg-Mn-Zn magnesium alloy in a phosphate buffered simulated body fluid (SBF) has been investigated by electrochemical testing and weight loss experiment for bone implant application. Long passivation stage and noble breakdown potential in the polarization curves indicated that a passive layer could be rapidly formed on the surface of magnesium alloy in the phosphate buffered SBF, which in turn can protect magnesium from fast corrosion. Surfaces of the immersed magnesium alloy were characterized by SEM, EDS, SAXS and XPS. Results have shown that Mg-Mn and Mg-Mn-Zn alloy were covered completely by an amorphous Mg-containing phosphate reaction layer after 24 h immersion. The corrosion behaviour of magnesium alloys can be described by the dissolving of magnesium through the reaction between magnesium and solution and the precipitating of Mg-containing phosphate on the magnesium surface. Weight loss rate and weight gain rate results have indicated that magnesium alloys were corroded seriously at the first 48 h while Mg-containing phosphate precipitated fast on the surface of magnesium alloy. After 48-96 h immersion, the corrosion reaction and the precipitation reaction reach a stable stage, displaying that the phosphate layer on magnesium surface, especially Zn-containing phosphate layer could provide effective protection for magnesium alloy.
TL;DR: In this paper, a developmental combustion outer casing was fabricated via a hybrid-manufacturing route, which included an internal, circumferential flange of Alloy 718, built up via an automated, high volumetric deposition rate MIG process.