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Highlights: [•] Cu47.5Zr47.5Al5 metallic glass has been surface laser treated at various conditions. [•] Changes in the microstructure, mechanical properties and wettability are examined. [•] Hardness variations are ascribed to free volume annihilation and phase formation. [•] Enhanced surface mechanical properties are observed under specific laser conditions. [ABSTRACT FROM AUTHOR]

Abstract: The effects of minor additions of Nb (2, 3 and 4at%) to the Ti40Zr10Cu38Pd12 alloy are discussed in terms of microstructure, thermal behavior, mechanical properties and corrosion resistance. The addition of Nb promotes the formation of nanocrystals, i.e., from a completely amorphous structure (when no Nb is added) to a mainly crystalline structure (for a 4% of Nb addition). The glassy alloy exhibits large hardness, relatively low Young''s modulus and excellent corrosion behavior, although the plasticity is rather limited. A significant increase in compressive plasticity (total strain over 13%) is achieved in the sample with 3% of Nb without compromising the strength. Young''s modulus of the as-cast alloy (around 100GPa, as determined from acoustic measurements) increases only slightly when disperse nanocrystallites are embedded in the amorphous matrix. Improvement of the corrosion performance, with delayed pitting corrosion, is also observed for 3% Nb addition. [Copyright &y& Elsevier]

Abstract: The influence of thermally-induced structural relaxation and crystallization on the mechanical and electrochemical corrosion behaviour of a Zr60Cu20Al10Fe5Ti5 metallic glass has been studied. The hardness, H, and reduced Young''s modulus, E r, increase upon annealing at 648 K (i.e., close to the glass transition) from H = 6.7 GPa and E r = 79.4 GPa (as-cast state) to H = 7.0 and E r = 86.7 GPa (structurally relaxed state). The influence of the free volume annihilation, caused by the annealing treatments, on these mechanical properties is discussed. Further increase in H and E r occurs after annealing at 873 K, when the sample becomes fully crystalline, probably due to the formation of Zr2Cu phase. The crystallization also increases the H/E r ratio (which is indicative of the wear resistance), from 0.083 in the as-cast condition to 0.102, whereas structural relaxation does not have a clear effect on this parameter. Annealing close to the glass transition is also beneficial to improve the corrosion resistance and, in particular, the resistance to pitting, when this alloy is immersed in simulated body fluid (Hank''s solution). The corrosion potential shifts from −0.214 V to −0.043 V (vs. Ag|AgCl) and the current density decreases from 3.017 × 10−4 A/cm2 to 8.846 × 10−6 A/cm2 after annealing at 648 K, mainly because of the free volume reduction. The corrosion potential is maximum (i.e., −0.022 V) and the corrosion density minimum (i.e., 1.428 × 10−6 A/cm2) when the sample becomes fully crystalline. [Copyright &y& Elsevier]

Abstract: The influence of partial substitution of Mg by Pd on the microstructure, mechanical properties and corrosion behaviour of Mg72−x Zn23Ca5Pd x  (x=0, 2 and 6 at.%) alloys, synthesized by copper mould casting, is investigated. While the Mg72Zn23Ca5 alloy is mainly amorphous, the addition of Pd decreases the glass-forming ability, thus favouring the formation of crystalline phases. From a mechanical viewpoint, the hardness increases with the addition of Pd, from 2.71 GPa for x=0 to 3.9 GPa for x=6, mainly due to the formation of high-strength phases. In turn, the wear resistance is maximized for an intermediate Pd content (i.e., Mg70Zn23Ca5Pd2). Corrosion tests in a simulated body fluid (Hank’s solution) indicate that Pd causes a shift in the corrosion potential towards more positive values, thus delaying the biodegradability of this alloy. Moreover, since the cytotoxic studies with mouse preosteoblasts do not show dead cells after culturing for 27 h, these alloys are potential candidates to be used as biomaterials. [Copyright &y& Elsevier]

Abstract: Tailoring of the mechanical properties (e.g., hardness, Young''s modulus or wear characteristics) of Co–Ni electrodeposits has been accomplished by changing the anion (sulphate versus chloride ions) in glycine-containing solutions at 80°C, while maintaining all the other electroplating conditions unaltered. Galvanostatic deposition on metalized silicon substrates at 5–40mAcm−2 produced well adherent Co–Ni films with varying surface finish, chemical composition (50–83wt% Co), morphology and structure. The deposition from chloride salts yielded matte grey, cobalt-rich Co–Ni films with hexagonal close-packed structure and crystallite sizes around 65–85nm. Films obtained under the same electrodeposition conditions from sulphate salts were Ni-rich, displayed smoother surfaces and smaller crystallite sizes (30–40nm) belonging mainly to the face-centered cubic phase. The crystallite size played a key role on the mechanical properties of the films, while the composition and the phase percentage had little effect. It is thus demonstrated that the nature of the anion induces a large tunability both in the microstructure and mechanical properties of the deposits. In particular, the nanoindentation hardness could be varied between 1.6 and 7.1GPa, while the Young''s modulus ranged between 122 and 181GPa. [Copyright &y& Elsevier]

Abstract: Ferromagnetic CoNiReP films (∼3μm in thickness) have been prepared by galvanostatic electrodeposition using direct current (DC) and reverse pulse plating (RPP) conditions. The composition, microstructure and mechanical and magnetic properties of these films strongly depend on the applied current density. The differences are particularly pronounced in the RPP-electroplated alloys, where amorphous films with 32at% Co showing soft-magnetic behavior and large hardness values (around 9GPa) are obtained at low cathodic current densities (j c), whereas fully crystalline hard-ferromagnetic CoNiReP alloys containing ∼80at% Co are produced at high j c. All DC-plated CoNiReP films exhibit crystalline microstructures with tunable grain size and texture, hard-magnetic properties (with perpendicular magnetic anisotropy) and mechanical hardness values around 7GPa. The magnetic properties of these Co-rich CoNiReP alloys are superior to those previously reported in electroless deposited Ni-rich CoNiReP. By applying suitable current densities, films with an intrinsic coercivity of 3.5kOe possessing a saturation magnetization around 800emucm−3 can be obtained from both DC and RPP deposition techniques. In addition, the films investigated in this work are thicker than electroless-plated CoNiReP alloys and can be grown in acidic pH values; thus they are suitable permanent magnetic materials for use in wirelessly actuated micro-electromechanical systems (MEMS). [Copyright &y& Elsevier]

Abstract: Cu1−x–Nix (0.43≤ x ≤1.0) films were electrodeposited from citrate–sulphate baths at different current densities onto Cu/Ti/Si (100) substrates with the addition of saccharine as a grain-refining agent. The Cu–Ni alloy films produced from saccharine-free baths were fine-grained (crystallite size of ~400nm). The addition of saccharine to the electrolytic solution induced a dramatic decrease in crystal size (down to ~27nm) along with a reduction in surface roughness. Although the effect of saccharine on pure Ni films was less obvious, significant changes were observed due to the presence of saccharine in the bath during the alloying of Cu with Ni. Compared to fine-grained Cu–Ni films, the nanocrystalline films exhibited lower microstrains and a larger amount of stacking faults as observed by X-ray diffraction. These features enhance the mechanical properties of the Cu–Ni alloys, making the nanocrystalline Cu–Ni films superior to both the corresponding fine-grained films and pure Ni films. In particular, hardness in fine-grained films varied from 4.2 (x =0.43) to 5.4GPa (x =0.86), whereas hardness varied between 6.7 and 8.2GPa for nanocrystalline films of similar composition. In addition, wear resistance and elastic recovery were enhanced. Nanostructuring did not significantly affect corrosion resistance of Cu–Ni alloys in chloride media. Although the corrosion potential shifted slightly towards more negative values, the corrosion current density decreased, thereby making the electrodeposition nanostructuring process an effective tool to improve the overall properties of the Cu–Ni system. [Copyright &y& Elsevier]

Abstract: The mapping of structural, magnetic, and mechanical properties of Co–W coatings galvanostatically electrodeposited from a citrate–borate bath is investigated. The intrinsic characteristics of the coatings, such as crystallite size or tungsten content are correlated with the extrinsic growth parameters, such as pH, complexes distribution, and current density. The increase in pH from 5 to 8 results in an increase of the W content in the deposits from 2at.% up to 36at.% in a controlled way, and it correlates with an increase in concentration of W(VI) complexes in the bath. The crystallite size estimated from XRD patterns, decreases from 39 to 5nm with increasing W content from 3 to 25at.% respectively. The obtained coatings show highly tunable mechanical and magnetic properties. The hardness increases with W content from ∼3GPa up to ∼13GPa. A semi-hard ferromagnetic behavior with a coercivity of ∼470Oe along the perpendicular-to-plane direction is observed for Co–W alloys containing small amounts of W in the range of ∼2–3at.%. At higher tungsten contents the coatings are magnetically softer, and the electrodeposits become non-ferromagnetic beyond ∼30at.% W. Because of this combination of physical properties, electrodeposited Co–W coatings may become suitable materials for multi-scale technologies. [Copyright &y& Elsevier]

Among W alloys, Fe-W has seen much attention recently, due to the need of moving toward the design of environmentally friendly materials. Coatings with 4, 16 and 24 at.% of W were electrodeposited from an environmental friendly Fe(III)-based glycolate-citrate bath. The samples were annealed in vacuum at different temperatures up to 800 °C. Different crystalline phases are formed upon annealing: α-Fe, Fe 2 W, Fe 3 W 3 C, Fe 6 W 6 C, and FeWO 4 . Their grain size and distribution within the coating was studied by means of Electron Backscattered Diffraction (EBSD) technique. The effect of annealing on the mechanical properties of the coatings was analyzed performing nanoindentation measurements. The results show a considerable increase of the hardness followed by a rapid decrease at higher temperatures. The highest hardness value, i.e. 16.5 GPa, is measured for the sample with 24 at.% of W after annealing at 600 °C owing to the precipitation of α-Fe crystallites. This study indicates the possibility to substantially increase the hardness of electrodeposited Fe-W coatings by optimization of the annealing treatment. In addition, the critical influence of the carbide and oxide phases on the mechanical properties of alloys is discussed. Hence, Fe-W coatings rich in W can be applied as a possible candidate for protective coating applications at elevated temperatures. [ABSTRACT FROM AUTHOR]

Porous Fe-30Mn6Si1Pd (wt.%) alloys were prepared by a simple press and sinter process from ball-milled Fe, Mn, Si and Pd powders blended with 10 wt%, 20 wt% and 40 wt% NaCl to obtain different degrees of porosity. For comparison purposes, a bulk fully-compact Fe-30Mn6Si1Pd alloy was produced by arc-melting and subsequent copper-mold suction-casting. While the porous Fe-30Mn6Si1Pd alloys only consist of γ-austenite, their fully-compact counterpart comprises ε-martensite and γ-austenite phases. In all cases, the low magnetic susceptibility response assures good compatibility with nuclear magnetic resonance and magnetic resonance imaging techniques. Furthermore, a reduction of the Young's modulus, from 55 to 7 GPa, was attained by introducing porosity. The biodegradation performance was evaluated by static immersion and electrochemical corrosion tests in Hank's solution. The influence of immersion time on composition, microstructure, mechanical and magnetic properties was assessed. While introducing porosity renders alloys with suitable mechanical and magnetic properties, it also has a detrimental effect in terms of cell viability. Hence, the porosity level needs to be controlled in order to obtain alloys with an optimized performance.∖ [ABSTRACT FROM AUTHOR]