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Liquid metal dealloying (LMD) is a new technology to create porous materials. From a (FeCr)x‐Ni1–x precursor, it is possible to get a bicontinuous structure of FeCr and Mg: a metal–metal composite. An etching step removes the Mg solid‐state solution phase to give a metal–air composite. The last step, polymer infiltration, gives metal–polymer composites. Herein, metal–metal, metal–air, and metal–polymer (rubbery or glassy polymers) with three different phase ratios are elaborated by LMD from Ni‐based precursors and their mechanical properties are analyzed. A full polymer infiltration into the pores is obtained and the epoxy polymer properties are not affected by the metallic foam presence. Concerning control of the mechanical properties, the material's second‐phase selection is a key factor. Herein, it is shown that the mechanical properties are easily designed by optimizing phase ratio, ligament size, and second‐phase type and that these materials are promising materials for biomedical applications. [ABSTRACT FROM AUTHOR]

Ti40Zr10Cu36Pd14 Bulk Metallic Glass (BMG) appears very attractive for future biomedical applications thanks to its high glass forming ability, the absence of toxic elements such as Ni, Al or Be and its good mechanical properties. For the first time, a complete and exhaustive characterization of a unique batch of this glassy alloy was performed, together with ISO standard mechanical tests on machined implant-abutment assemblies. The results were compared to the benchmark Ti-6Al-4V ELI (Extra-Low-Interstitial) to assess its potential in dental implantology. The thermal stability, corrosion and sterilization resistance, cytocompatibility and mechanical properties were measured on samples with a simple geometry, but also on implant-abutment assemblies’ prototypes. Results show that the glassy alloy exhibits a quite high thermal stability, with a temperature range of 38 °C between the glass transition and crystallization, a compressive strength of 2 GPa, a certain plastic deformation (0.7%), a hardness of 5.5 GPa and a toughness of 56 MPa.√m. Moreover, the alloy shows a relatively lower Young’s modulus (96 GPa) than the Ti-6Al-4V alloy (110–115 GPa), which is beneficial to limit bone stress shielding. The BMG shows a satisfactory cytocompatibility, a high resistance to sterilization and a good corrosion resistance (corrosion potential of −0.07 V/SCE and corrosion current density of 6.0 nA/cm2), which may ensure its use as a biomaterial. Tests on dental implants reveal a load to failure 1.5-times higher than that of Ti-6Al-4V and a comparable fatigue limit. Moreover, implants could be machined and sandblasted by methods usually conducted for titanium implants, without significant degradation of their amorphous nature. All these properties place this metallic glass among a promising class of materials for mechanically-challenging applications such as dental implants. [ABSTRACT FROM AUTHOR]

In this paper, in-situ β-Ti phase reinforced (Al, Ni, Be)-free Ti-based bulk metallic glass matrix composites (BMGMCs) were developed by microalloying Mo. The BMGMCs showed higher fracture strength and larger plastic strain than the monolithic glassy counterpart and other Be-free Ti-based BMGMCs, under both compression and bending tests. The ductile and soft β-Ti secondary phase appeared to hinder the rapid propagation of the main shear band, improving the plasticity. Furthermore, the size and interparticle spacing of the secondary β-Ti were very close to the processing zone size, further stabilizing the shear band against developing into cracks and thus improving mechanical properties. But under tension, no obvious ductilization was observed for the BMGMCs, maybe resulting from the lower volume fraction of β-Ti phase because of higher cooling rate during the fabrication for them. Further work should be focused on optimizing the composition and increasing the volume fraction of β-Ti phase and sample size. [ABSTRACT FROM AUTHOR]

In-situ Ti-reinforced Mg-based (MT-D) and in-situ Ta-reinforced Zr-based (ZT-D) bulk metallic glass matrix composites (BMGMCs) were prepared by a novel dealloying method, which contains an element-selective leaching process in a metallic melt. The BMGMCs exhibit better mechanical properties, including higher fracture strength and larger plastic strain, than their monolithic glassy counterparts or similar BMGMCs by ex-situ dispersing or conventional arc-melting methods. The differences of Young's modulus between the dispersoids and the glassy matrix for these BMGMCs generate stress concentration at the interface, which is considered to suppress the propagation of the single main shear band and initiate multiple shear bands to accommodate the plastic deformation. Furthermore, the fine size of dispersoids for these BMGMCs, caused by low reaction temperature during dealloying in the metallic melt, results in more interfaces with the matrix for further improvement of mechanical properties. In addition, the low reaction temperature can also contribute to less composition fluctuation of the matrix to maintain the glass-forming ability of itself, which can introduce no undesired phases to degrade the mechanical properties. This novel in-situ dealloying method is believed to make a breakthrough in designing ductile BMGMCs with fine-sized secondary particles. [ABSTRACT FROM AUTHOR]

A NiTi/Mg composite was fabricated using a method that combines top-down pore-forming and pressureless infiltration processes. The phase constituents of this simple composite are B2-NiTi, B19′-NiTi and Mg phases. Both the size and the distribution of the Mg-phase are fine and homogeneous. The composite has very high mechanical strength and damping capacity, ~1.2 and 1.5-fold higher than those of a similar composite with different microstructures, respectively. These behaviors are generally attributed to the high damping capacity of Mg, the physical continuity of the composite, and the homogeneous distribution of fine Mg-phase, which generate more interfaces, contributing to the damping capacity. This composite is considered a good candidate for use as a damping material in engineering applications. [ABSTRACT FROM AUTHOR]

Abstract: Heat evolution of stress-induced structural disorder ΔH s(ε) of a Zr55Al10Ni5Cu30 bulk metallic glass (BMG) during compressive constant ram-velocity deformation in the glass transition region (T g =680K) was deduced from in situ measurements of temperature change ΔT(ε) of deforming samples, where ε is true strain. At transition from the linear to nonlinear viscoelasticity, i.e., a softening phenomenon, viscosity η(ε) does not change consistently with ΔT(ε) but with ΔH s(ε). Therefore, it is concluded that the stress-induced structural disorder triggered this softening phenomenon. The viscous frictional heating of the softened alloy brings about the increase in ΔT, which also influences ΔH s. Because ΔT is determined by relationship between the power of the frictional heating and heat convection to the sample-surroundings, ΔH s and η can be positively controlled with varying thermal conductivity D of the surrounding materials, especially after the transition period. [Copyright &y& Elsevier]

The structure of an arc-melted ingot of the Ti50Ni20Cu20Nb10 alloy of about 30 mm diameter and 10 mm height was studied by X-ray diffractometry, transmission electron microscopy (TEM). Mechanical properties were tested by an Instron-type testing machine. The ingot sample has a disperse submicron-size complex eutectic structure (including ternary eutectic) consisting of a quaternary β-(Ti, Nb, Ni, Cu) solid solution, a monoclinic TiNi-type (Ti, Nb)(Ni, Cu) phase and a (Ti, Nb)2(Cu, Ni) phase which is a solution of Nb (replacing Ti) and Ni (replacing Cu) in the tetragonal Ti2Cu phase. The sample exhibits high mechanical properties and does not require additional mold injection casting procedure to obtain fine microstructure. [Copyright &y& Elsevier]

The mechanical properties, glass-forming ability, supercooled liquid region and devitrification behaviour of the Cu–Zr–Ti–(Pd, Ag, Pt and Au) bulk glass formers were studied by using a mechanical testing machine, X-ray diffraction, transmission electron microscopy, differential scanning calorimetry and isothermal calorimetry. The bulk glassy alloys of diameter 2 mm were formed in the Cu55Zr30Ti10Pd5 and Cu55Zr30Ti10Ag5 alloys while Cu55Zr30Ti10Au5 bulk alloy showed mixed glassy and crystalline structure. No glassy phase was formed in the Cu55Zr30Ti10Pt5 bulk alloy whereas the glassy phase was formed in all of the ribbon samples prepared by rapid solidification. The studied alloys except for the Pt-bearing one have slightly increased compressive fracture or yield strength values compared to ternary Cu60Zr30Ti10 glassy alloy. At the same time Pd and Au addition significantly expand the supercooled liquid region of Cu–Zr–Ti glassy alloy and increase Young''s modulus. A nanoicosahedral phase is primarily formed in the Cu55Zr30Ti10(Pd,Au)5 glassy alloys in the initial stage of the devitrification process by nucleation and three-dimensional diffusion-controlled growth. Nearly the same quasilattice constant obtained in the Cu55Zr30Ti10(Pd,Au)5 alloys illustrates the same type of the icosahedral phase in these alloys. However, no icosahedral phase was found in the Cu55Zr30Ti10(Ag,Pt)5 alloys. [Copyright &y& Elsevier]

New AlxCo50−xCu50−xMnx (x = 2.5, 10, and 15 atomic %, at%) immiscible medium-entropy alloys (IMMEAs) were designed based on the cobalt-copper binary system. Aluminum, a strong B2 phase former, was added to enhance yield strength and ultimate tensile strength, while manganese was added for additional solid solution strengthening. In this work, the microstructural evolution and mechanical properties of the designed Al-Co-Cu-Mn system are examined. The alloys exhibit phase separation into dual face-centered cubic (FCC) phases due to the miscibility gap of the cobalt-copper binary system with the formation of CoAl-rich B2 phases. The hard B2 phases significantly contribute to the strength of the alloys, whereas the dual FCC phases contribute to elongation mitigating brittle fracture. Consequently, analysis of the Al-Co-Cu-Mn B2-strengthened IMMEAs suggest that the new alloy design methodology results in a good combination of strength and ductility. [ABSTRACT FROM AUTHOR]

Abstract: The Mg-3.5Zn-0.6Gd (at. %) alloy was prepared and homogenized at 673K for 8h, and then extruded at 523K with an extrusion ratio of 9:1. The microstructure and mechanical properties of the extruded alloy have been investigated. Icosahedral quasicrystalline phase (I-phase) existed in extruded Mg–Zn–Gd-based alloys in two morphologies: (1) micron-scale I-phase formed in the solidification, (2) nano-scale ellipsoid-shape I-phase particles precipitated in the extrusion process. A definite orientation relationship and good atomic match between I-phase and α-Mg matrix were directly observed by conventional and high-resolution transmission electron microscopy (HRTEM), which contribute to the high tensile strength of 308MPa and the large plasticity of 16.4%. [Copyright &y& Elsevier]

Abstract: In the glassy temperature region from ambient to the glass transition temperature (T g), an apparent Young''s modulus (E ap), the slope of the initial linear part on the stress–strain curve, in a Zr-based metallic glass clearly depends on both temperature and strain rate, especially above 0.87 T g. This indicates that viscous contribution is included in this apparent elastic response. If yield strain is deduced with Young''s modulus measured by the ultrasonic vibration method, which excludes the viscous contribution, temperature dependence of the yield strain can be captured well with the Argon''s Shear Transformation Zone (STZ) model. On the other hand if the yield strain is deduced with E ap, the strain was found to keep the “universal” critical value ∼0.020 for many metallic glasses at the ambient temperature. This may indicate another clue to understand the yield mechanism on BMG. [Copyright &y& Elsevier]

Rising demand for bone implants has led to the focus on future alternatives of alloys with better biocompatibility and mechanical strength. Thus, this research is dedicated to the synthesis and investigation of new compositions for low-alloyed Ti-based compounds, which conjoin relatively acceptable mechanical properties and low elastic moduli. In this regard, the structural and mechanical properties of α + β Ti-Fe-Cu-Sn alloys are described in the present paper. The alloys were fabricated by arc-melting and tilt-casting techniques which followed subsequent thermo-mechanical treatment aided by dual-axial forging and rolling procedures. The effect of the concentrations of the alloying elements, and other parameters, such as regimes of rolling and dual-axial forging operation, on the microstructure and mechanical properties were thoroughly investigated. The Ti94Fe1Cu1Sn4 alloy with the most promising mechanical properties was subjected to thermo-mechanical treatment. After a single rolling procedure at 750 °C, the alloy exhibited tensile strength and tensile plasticity of 1300 MPa and 6%, respectively, with an elastic modulus of 70 GPa. Such good tensile mechanical properties are explained by the optimal volume fraction balance between α and β phases and the texture alignment obtained, providing superior alternatives in comparison to pure α- titanium alloys. [ABSTRACT FROM AUTHOR]

Abstract Porous Ni- and Be-free Ti-based (Ti 45 Zr 10 Cu 31 Pd 10 Sn 4) bulk metallic glass (BMG) with a diameter exceeding 15 mm was developed by spark plasma sintering (SPS) the mixture of gas-atomized Ti-based glassy alloy powder and solid salt (NaCl) powder, followed by leaching treatment to eliminate the salt phase. The thermal and structural stability, microstructure, mechanical properties, corrosion behavior, and biocompatibility of the developed porous Ti-based BMG samples were investigated systematically. The developed porous Ti-based BMG alloy exhibited three times higher yield strength than that of the natural bone, simultaneously matched the Young's modulus of natural bone, and demonstrated high corrosion resistance and excellent biocompatibility. These results suggest that porous Ti-based BMGs produced by the SPS process open an advanced alternative for clinical applications under load-bearing conditions such as surgical implants. Highlights • Porous Ti-based bulk metallic glasses were developed by spark plasma sintering. • Porous Ti-based BMGs exhibited high strength and matched Young's modulus of natural bone. • Porous Ti-based BMGs demonstrated high corrosion resistance and excellent biocompatibility. [ABSTRACT FROM AUTHOR]

Abstract Biomaterials are attracting an ever-increasing research interest. As part of this overall effort, we report herein the fabrication and characteristics of Zr-based ribbon samples with three different compositions: Zr 56 Co 28 Ga 16 , Zr 56 Co 28 Ga 14 Si 2 , and Zr 56 Co 28 Ga 14 Sn 2. The supercooled-liquid region Δ T = T x − T g of these materials is 16, 18, and 29 K, respectively, where T x is the temperature of the onset of crystallization and T g is the glass-transition temperature. The samples are thermally characterized by using differential scanning calorimetry and by determining the activation energy. The corrosion resistance is determined by immersing the materials for up to 20 days in a simulated body fluid, and the cytotoxicity is measured from the proliferation of osteoblast-like cells on the samples. Finally, the mechanical properties are investigated by nanoindentation. The Young's modulus is 112 GPa. These results all highlight the suitability of this metallic glass for biomedical applications. Highlights • A new, Zr-based metallic glass was elaborated as biomaterials, without Fe, Ni or Al. • Replacing Al by Ga was investigated and biocompatibility of the alloy is promising. • This Zr-glass exhibits a good thermal stability and good corrosion resistance. • Additions of Si/ Sn in the system increase corrosion resistance and biocompatibility. • Young modulus is lower than that of common crystalline alloys used as biomaterials. [ABSTRACT FROM AUTHOR]

The relatively low density of Ti (4.5 Mg/m3) implies high strength/density ratio for Ti-based alloys. A composite Ti65Fe35 alloy produced in the shape of arc-melted ingot of about 20 mm in diameter and 10 mm in height exhibits a high mechanical strength of 2.2 GPa at 6.7% ductility and a Young’s modulus of 149 GPa. Its microstructure consists of the cubic TiFe phase and a supersaturated BCC β-Ti solid solution. The formation of a supersaturated β-Ti solid solution and the disperse eutectic structure obtained result in a high strength of the Ti–Fe alloy which in addition to that has much higher ductility compared to that of nanostructured and glassy alloys. The Ti–Fe alloy is characterized by low cost of the alloying elements and does not require an additional injection mould casting procedure. [Copyright &y& Elsevier]

Abstract: The high strength metastable Ti–Fe–Co alloys were produced by arc-melting in the shape of distorted semi-spherical ingots with the dimensions of about 25–30mm in diameter and 7–10mm in height. The structure of the hypereutectic Ti–Fe–Co alloys (at Fe/Co ratio ≥1) studied by X-ray diffractometry and scanning electron microscopy consisted of the primary dendrites of an ordered cP2 Ti(Fe, Co) compound and an eutectic consisting of the cP2 Ti(Fe, Co) compound and a disordered BCC cI2 β-Ti solid solution. The strongest Ti–Fe–Co alloys have a hypereutectic structure and exhibit a high strength exceeding 2000MPa and a plastic deformation of about 15%. The quaternary Ti67Fe14Co14Sn5 alloy exhibits a high strength of 1830MPa and the largest plastic strain of 24%. The deformation behavior and the fractography of Ti–Fe–Co and Ti–Fe–Co–Sn alloys are studied in detail. The formation of a composite-like structure with hard carcass of the intermetallic phase in the relatively soft eutectic matrix enabled both high strength and ductility. The accommodation deformation can be explained by the intergranular sliding of the primary Ti(Fe, Co) dendrites in the softer eutectic matrix. Rough primary dendrites and eutectic rods of the cP2 intermetallic phase act as efficient barriers for shear strain and cracks propagation, while fine eutectic rods of submicron size are quite effortlessly cut by deformation bands and cracks. It is shown that the high strength and ductility values for Ti-based alloys can be achieved without using the injection mould casting or rapid solidification procedure. [Copyright &y& Elsevier]

Abstract: High-strength Ti–Fe–Co alloys were produced in the shape of arc-melted ingots with the dimensions of about 20–25mm in diameter and 7–10mm in height. The structure of the Ti–Fe–Co alloys (at Fe/Co ratio >1) studied by X-ray diffractometry and scanning electron microscopy consisted of an ordered Ti(FeCo) compound and a disordered body-centered cubic β-Ti solid solution. The optimization of the Ti–Fe–Co alloy composition is performed from the viewpoint of both high strength and ductility. The strongest Ti–Fe–Co alloys have a hypereutectic structure and exhibit a high strength of about 2000MPa and a plastic deformation of 15%. The high strength and ductility values can be achieved without using the injection mould casting or rapid solidification procedure. The deformation behavior and the fractography of Ti–Fe–Co alloys are studied in detail. [Copyright &y& Elsevier]

Abstract Here we report on the structure and mechanical properties of low-alloyed Ti-based alloys containing Ag subjected to a dual-axial forging operation. The dependence of the microstructure and mechanical properties on the regimes of the dual-axial forging operation is studied for the Ti 94 Ag 3 Pd 3 alloy having the optimal properties. The hemolytical activity of the Ti 94 Ag 3 Pd 3 alloy was also investigated. The percent hemolysis induced by the sample after 5 h of incubation is much lower than that for the surgical titanium after 4 h of incubation. Doping of the Ti 94 Ag 3 Pd 3 by a minor amount of nitrogen (N) improved its mechanical properties and decreased its elastic modulus (to 65 MPa), which is attractive for biological applications. Highlights • Ti 94 Ag 3 Pd 3 alloy showed the most attractive mechanical properties. • Hemolysis induced by Ti 94 Ag 3 Pd 3 is much lower than that induced by titanium. • Nitrogen improved mechanical properties of the Ti 94 Ag 3 Pd 3 alloy. • Tensile strength is more than 1000 MPa, the elongation is about 15%. • The elastic modulus is 65 MPa. [ABSTRACT FROM AUTHOR]

Ti40Zr10Cu36Pd14 Bulk Metallic Glass (BMG) appears very attractive for future biomedical applications thanks to its high glass forming ability, the absence of toxic elements such as Ni, Al or Be and its good mechanical properties. For the first time, a complete and exhaustive characterization of a unique batch of this glassy alloy was performed, together with ISO standard mechanical tests on machined implant-abutment assemblies. The results were compared to the benchmark Ti-6Al-4V ELI (Extra-Low-Interstitial) to assess its potential in dental implantology. The thermal stability, corrosion and sterilization resistance, cytocompatibility and mechanical properties were measured on samples with a simple geometry, but also on implant-abutment assemblies’ prototypes. Results show that the glassy alloy exhibits a quite high thermal stability, with a temperature range of 38 °C between the glass transition and crystallization, a compressive strength of 2 GPa, a certain plastic deformation (0.7%), a hardness of 5.5 GPa and a toughness of 56 MPa.√m. Moreover, the alloy shows a relatively lower Young’s modulus (96 GPa) than the Ti-6Al-4V alloy (110–115 GPa), which is beneficial to limit bone stress shielding. The BMG shows a satisfactory cytocompatibility, a high resistance to sterilization and a good corrosion resistance (corrosion potential of −0.07 V/SCE and corrosion current density of 6.0 nA/cm2), which may ensure its use as a biomaterial. Tests on dental implants reveal a load to failure 1.5-times higher than that of Ti-6Al-4V and a comparable fatigue limit. Moreover, implants could be machined and sandblasted by methods usually conducted for titanium implants, without significant degradation of their amorphous nature. All these properties place this metallic glass among a promising class of materials for mechanically-challenging applications such as dental implants. [ABSTRACT FROM AUTHOR]

• A novel Fe-Ni-Co-Mn-Ti-Si MEA strengthened by heterogeneous microstructure was developed. • A superior combination of high-strength (YS ~ 930 MPa and UTS ~ 1075 MPa) and ductility (30%) has been achieved. • The deformation-induced martensitic transformation occurs during the straining of samples. • HDI and high plastic-incompatibility between the martensite and austenitic contributes to the high strength and ductility. In the work reported here, the mechanical properties of a newly developed Fe-Ni-Co-Mn-Ti-Si medium-entropy alloy with heterogeneous microstructure were investigated. High yield strength (~930 MPa), high ultimate tensile strength (~1100 MPa), and good ductility (~30%) were achieved using hetero-deformation-induced strengthening and high plastic-incompatibility between mechanically induced-martensite and the austenitic matrix. [ABSTRACT FROM AUTHOR]