Search Results (46)

Titanium-based bulk metallic glasses (BMGs) offer high strength, lower stiffness than Ti-6Al-4V, and superior corrosion resistance, but conventional Ti glass-forming systems often contain toxic Ni, Be, or Cu. This work investigates five novel Ti-based alloys free of these elements—Ti₄₂Zr₃₅Si₅Co_12.5Sn_2.5Ta₃, Ti₄₂Zr₄₀Ta₃Si₁₅, Ti₆₀Nb₁₅Zr₁₀Si₁₅, Ti₃₉Zr₃₂Si₂₉, and Ti_65.5Fe_22.5Si₁₂—synthesized by arc melting and suction casting. Single-track laser remelting using a selective laser melting (SLM) system was performed to simulate additive manufacturing and examine microstructural evolution, cracking behavior, mechanical properties, and cytocompatibility. All alloys solidified into fully crystalline α/β-Ti matrices with Ti/Zr silicides; no amorphous structures were obtained. Laser remelting refined the microstructure but did not induce glass formation, consistent with the known limited glass-forming ability of Cu/Ni/Be-free Ti systems. Cracking was observed at low laser energies but crack density decreased as laser energy increased. Cracks were eliminated above ~0.4 J/mm for most alloys. Ti₄₂Zr₃₅Si₅Co_12.5Sn_2.5Ta₃ exhibited the lowest stiffness (~125 GPa), while Ti₆₀Nb₁₅Zr₁₀Si₁₅ showed the highest due to silicide precipitation. Cytotoxicity tests (ISO 10993-5) confirmed all alloys to be non-toxic, with some extracts even enhancing fibroblast proliferation. This rapid laser-remelting approach enables cost-effective screening of Ti-based glass-forming alloys for additive manufacturing. Ti–Zr–Ta–Si systems demonstrated the most promising properties for further testing using the powder bed method. Full article

Metallic glass alloys exhibit excellent properties, yet suffer from poor room-temperature plasticity, a limitation that restricts their engineering applications. Bulk metallic glass matrix composites (BMGMCs) have proven effective in enhancing the plasticity of metallic glasses, and the addition of alloying elements serves as a key strategy to regulate their microstructure and optimize the properties of these composites. This study aims to investigate the effects of a vanadium (V) addition on the mechanical properties and microstructure of Ti-based BMGMCs, while exploring the underlying mechanism of V’s influence. Using (Ti₅₁Zr₂₅Cu₆Be₁₈)_100−xV_x (x = 0, 4, 8, 12, 16, 20) BMGMCs as test specimens, microstructural characterization was performed via X-ray diffraction (XRD) and scanning electron microscopy (SEM), and compressive mechanical properties were tested. The results indicate that a V addition refines dendrites without altering the phase composition, which remains composed of β-Ti crystals and an amorphous matrix. With the increase in V content, the compressive plastic strain shows a trend of first increasing and then decreasing; when x = 12, the specimen exhibits the maximum compressive plastic strain, reaching 7.9%. Additionally, the volume fraction of the crystalline phase gradually increases with increasing V content. This study clarifies the mechanism by which V regulates the microstructure and properties of Ti-based BMGMCs, thereby providing theoretical and experimental insights for optimizing alloy compositions to enhance the mechanical performance. Full article

This study explores the enhancement of antimicrobial and biomedical properties in Fe-based bulk metallic glasses (BMGs) through the addition of Ag. Fe_55-xCr₂₀Mo₅P₁₃C₇Ag_x (x = 0, 1, 2, 3 at.%) master alloy ingots were synthesized by the induction melting technique and industrial-grade raw materials, the master alloy ingots were prepared as bulk metallic glasses (referred to as Ag0, Ag1, Ag2, and Ag3) by the water-cooled copper-mold suction casting technique, and their glass-forming ability, corrosion resistance, biocompatibility, and antimicrobial properties were systematically investigated. The results indicate that the glass forming ability (GFA) decreased with increasing Ag content, reducing the critical diameter for fully amorphous formation from 2.0 mm for Ag0 to 1.0 mm for Ag3. Electrochemical tests in Hank’s solution revealed the superior corrosion resistance of the Fe-based BMGs as compared with conventional 316 L stainless steel (316L SS) and Ti6Al4V alloy (TC4), with Ag3 demonstrating the lowest corrosion current density and the most stable passivation. Biocompatibility assessments, including fibroblast cell viability and adhesion tests, showed enhanced cellular activity and morphology on Fe-based BMG surfaces as compared with 316L SS and TC4, with minimal harmful ion release. Antimicrobial tests against E. coli and S. aureus revealed significantly improved performance with the Ag addition, achieving bacterial inhibition rates of up to 87.5% and 86.7%, respectively, attributed to Ag⁺-induced reactive oxygen species (ROS) production. With their excellent corrosion resistance, biocompatibility, and antimicrobial activity, the present Ag-containing Fe-based BMGs, particularly Ag3, are promising candidates for next-generation biomedical implants. Full article

In the present investigation, high stability Vitreloy Zr₄₄Ti₁₁Cu₁₀Ni₁₀Be₂₅ bulk metallic glass has been subjected to severe shear deformation by high-pressure torsion for 0.1 revolutions under an applied pressure of 4 and 8 GPa. The fully glassy nature of the as-cast glass has been confirmed by X-ray powder diffraction and differential scanning calorimetry. Deformation-induced surface features on an internal plane of the deformed disk-shaped specimens were studied in detail at the macroscopic level by optical reconstruction method and at microscopic scales by white-light optical profilometry. Shear and compressive strain components were measured based on surface changes and it was determined that compressive strain gradient with 0.2–0.4 strain change builds up toward the disk edge, while only part of the nominal shear deformation occurs in the disk interior. The effect of strain localization in the Vitreloy bulk metallic glasses has been quantified by a surface distortion model based on simple shear. The model was then validated experimentally by the reconstructed z-profiles. Full article

The effects of a small addition of Ag and Ti on the thermal stability, mechanical properties, and tribological behavior of Zr-Co-Al bulk metallic glass (BMG) were investigated. A 5 at.% addition of Ag and Ti to the Zr-Co-Al base alloy improved the thermal stability and had no significant effect on the mechanical properties but considerably improved the wear behavior. The coefficient of friction decreased while the wear rate increased with increasing normal loads for all three alloys. Zr-Co-Al-Ti showed the best tribological performance among the studied alloys, with coefficient of friction and wear rate lower by a factor of four compared to Zr-Co-Al BMG. Predominantly oxidative wear was seen for the quaternary Zr-Co-Al-Ag and Zr-Co-Al-Ti BMGs at higher loads in contrast to abrasive and adhesive wear for the ternary Zr-Co-Al base alloy. These results highlight the potential of Ag and Ti micro-alloying for improving the mechanical and tribological properties of Zr-based amorphous alloys. Full article

This article reviews the research and development focus of metallic glasses in the field of biomedical applications. Metallic glasses exhibit a short-range ordered and long-range disordered glassy structure at the microscopic level, devoid of structural defects such as dislocations and grain boundaries. Therefore, they possess advantages such as high strength, toughness, and corrosion resistance, combining characteristics of both metals and glasses. This novel alloy system has found applications in the field of biomedical materials due to its excellent comprehensive performance. This review discusses the applications of Ti-based bulk metallic glasses in load-bearing implants such as bone plates and screws for long-term implantation. On the other hand, Mg-based metallic glasses, owing to their degradability, are primarily used in degradable bone nails, plates, and vascular stents. However, metallic glasses as biomaterials still face certain challenges. The Young’s modulus value of Ti-based metallic glasses is higher than that of human bones, leading to stress-shielding effects. Meanwhile, Mg-based metallic glasses degrade too quickly, resulting in the premature loss of mechanical properties and the formation of numerous bubbles, which hinder tissue healing. To address these issues, we propose the following development directions: (1) Introducing porous structures into titanium-based metallic glasses is an important research direction for reducing Young’s modulus; (2) To enhance the bioactivity of implant material surfaces, the surface modification of titanium-based metallic glasses is essential. (3) Developing antibacterial coatings and incorporating antibacterial metal elements into the alloys is essential to maintain the long-term effective antibacterial properties of metallic biomaterials. (4) Corrosion resistance must be further improved through the preparation of composite materials, while ensuring biocompatibility and safety, to achieve controllable degradation rates and degradation modes. Full article

Ti-based bulk metallic glass composites (BMGMCs) containing an in situ formed metastable β phase normally exhibit enhanced plasticity attributed to induced phase transformation or twinning. However, the underlying deformation micromechanism remains controversial. This study investigates a novel deformation mechanism of Ti-based BMGMCs with a composition of Ti_42.3Zr₂₈Cu_8.3Nb_4.7Ni_1.7Be₁₅ (at%). The microstructures after tension were analyzed using advanced electron microscopy. The dendrites were homogeneously distributed in the glassy matrix with a volume fraction of 55 ± 2% and a size of 1~5 μm. The BMGMCs deformed in a serrated manner with a fracture strength (σ_f) of ~1710 MPa and a fracture strain of ~7.1%, accompanying strain hardening. The plastic deformation beyond yielding was achieved by a synergistic action, which includes shear banding, localized amorphization and a localized BCC (β-Ti) to HCP (α-Ti) structural transition. The localized amorphization was caused by high local strain rates during shear band extension from the amorphous matrix to the crystalline reinforcements. The localized structural transition from BCC to HCP resulted from accumulating concentrated stress during deformation. The synergistic action enriches our understanding of the deformation mechanism of Ti-based BMGMCs and also sheds light on material design and performance improvement. Full article

In order to optimize the balance between strength and toughness, a series of multilayered Ti-based bulk metallic glass composites (BMGCs) with varying thicknesses of Ti-rich layers were successfully fabricated. The findings reveal that with an increase in the thickness of the Ti-rich layers, both the flexural yield strength and ultimate strength decreased from 2066 MPa and 2717 MPa to 668 MPa and 1163 MPa, respectively. Conversely, there was a noticeable increase in flexural strain. The fracture toughness of these multilayered Ti-based BMGCs decreased as the thickness of the Ti-rich layers increased; nevertheless, it stabilized at approximately 80 MPa·m^1/2 when the thickness reached 100 μm. It was observed that a shift in the dominant deformation mode may be accountable for this phenomenon. These noteworthy characteristics suggest that adjusting the thickness of Ti-rich layers in multilayered BMGCs can effectively optimize mechanical performance, shedding light on the manufacturing of novel BMGCs with high performance. Full article

A series of Ti₄₁Zr₂₅Be_34-xNi_x (x = 4, 6, 8, 10 at.%) and Ti₄₁Zr₂₅Be_34-xCu_x (x = 4, 6, 8 at.%) bulk metallic glasses were investigated to examine the influence of Ni and Cu content on the viscosity, thermoplastic formability, and nanoindentation of Ti-based bulk metallic glasses. The results demonstrate that Ti₄₁Zr₂₅Be₃₀Ni₄ and Ti₄₁Zr₂₅Be₂₆Cu₈ amorphous alloys have superior thermoplastic formability among the Ti₄₁Zr₂₅Be_34-xNi_x and Ti₄₁Zr₂₅Be_34-xCu_x amorphous alloys due to their low viscosity in the supercooled liquid region and wider supercooled liquid region. The hardness and modulus exhibit obvious variations with increasing Ni and Cu content in Ti-based bulk metallic glasses, which can be attributed to alterations in atomic density. Optimal amounts of Ni and Cu in Ti-based bulk metallic glasses enhance thermoplastic formability and mechanical properties. The influence of Ni and Cu content on the hardness of Ti-based bulk metallic glasses is discussed from the perspective of the mean atomic distance. Full article

Ti-based bulk metallic glasses are promising materials for metallic bone implants, mainly due to their mechanical biofunctionality. A major drawback is their limited corrosion resistance, with high sensitivity to pitting. Thus, effective surface treatments for these alloys must be developed. This work investigates the electrochemical treatment feasibility of nitric acid (HNO₃) solution for two bulk glass-forming alloys. The surface states obtained at different anodic potentials are characterized with electron microscopy and Auger electron spectroscopy. The corrosion behavior of the treated glassy alloys is analyzed via comparison to non-treated states in phosphate-buffered saline solution (PBS) at 37 °C. For the glassy Ti₄₇Zr_7.5Cu₃₈Fe_2.5Sn₂Si₁Ag₂ alloy, the pre-treatment causes pseudo-dealloying, with a transformation from naturally passivated surfaces to Ti- and Zr-oxide nanoporous layers and Cu-species removal from the near-surface regions. This results in effective suppression of chloride-induced pitting in PBS. The glassy Ti₄₀Zr₁₀Cu₃₄Pd₁₄Sn₂ alloy shows lower free corrosion activity in HNO₃ and PBS due to Pd stabilizing its strong passivity. However, this alloy undergoes pitting under anodic conditions. Surface pre-treatment results in Cu depletion but causes enrichment of Pd species and non-homogeneous surface oxidation. Therefore, for this glassy alloy, pitting cannot be completely inhibited in PBS. Concluding, anodic treatments in HNO₃ are more suitable for Pd-free glassy Ti-based alloys. Full article

Ti-based metallic glasses have a high potential for implant applications. The feasibility of a new biocompatible Ti-based bulk metallic glass composite for selective laser melting (SLM) had been examined. Therefore, it is necessary to design a high-glass-forming-ability Ti-based metallic glass (∆T_x = 81 K, γ = 0.427, γ_m = 0.763), to fabricate a partial glass-formable spherical powder (the volume fraction of the amorphous phase in the atomized Ti-based powders being 73% [size < 25 μm], 61% [25–37 μm], and 50% [37–44 μm]), and establish an SLM parameter (a scan rate of 600 mm/s, a power of 120 W, and an overlap of 10%). The Ti₄₂Zr₃₅Si₅Co_12.5Sn_2.5Ta₃ bulk metallic glass composite was successfully fabricated through SLM. This study demonstrates that the TiZrSiCoSnTa system constitutes a promising basis for the additive manufacturing process in terms of preparing biocompatible metallic glass composites into complicated graded foam shapes. Full article

Ti-based bulk metallic glass (BMG) alloys have attracted widespread attention due to their strong glass forming ability, high specific strength, and good corrosion resistance. However, the poor plasticity of BMGs limits their further application in the aerospace and aircraft fields, as well as others. We optimized the composition of SiC-reinforced, Ti-based metallic glass matrix composites (MGMCs) through finite element modeling (FEM). FEM of MGMCs containing irregularly shaped SiC particles with different contents was conducted. Stress and strain analyses were conducted to evaluate the effect of the particle volume fraction on the mechanical behavior of MGMCs, and an optimization value of 30% was obtained, which is conducive to plasticity improvement. Arc melting copper mold injection casting was used to verify the optimized SiC content. The results show that the electroless nickel plating treatment effectively improves the wettability between SiC particles and the amorphous matrix, enabling the successful preparation of SiC/MGMC with a volume fraction of 29.5% through traditional injection casting. The volume fraction of SiC plays a crucial role in the transition of fracture mode from splitting to shear in MGMCs. After adding lightweight SiC particles, the yield strength, plasticity, modulus, and specific strength were improved by 25%, 1471%, 46%, and 33%, indicating that the use of nickel-plated SiC particles in MGMCs is an effective strengthening and toughening method for BMGs. Full article

The continuous development of novel materials for biomedical applications is resulting in an increasingly better prognosis for patients. The application of more advanced materials relates to fewer complications and a desirable higher percentage of successful treatments. New, innovative materials being considered for biomedical applications are metallic alloys with an amorphous internal structure called metallic glasses. They are currently in a dynamic phase of development both in terms of formulating new chemical compositions and testing their properties in terms of intended biocompatibility. This review article intends to synthesize the latest research results in the field of biocompatible metallic glasses to create a more coherent picture of these materials. It summarizes and discusses the most recent findings in the areas of mechanical properties, corrosion resistance, in vitro cellular studies, antibacterial properties, and in vivo animal studies. Results are collected mainly for the most popular metallic glasses manufactured as thin films, coatings, and in bulk form. Considered materials include alloys based on zirconium and titanium, as well as new promising ones based on magnesium, tantalum, and palladium. From the properties of the examined metallic glasses, possible areas of application and further research directions to fill existing gaps are proposed. Full article

An ultra-strong Ti-based bulk metallic glass composite was developed via the transformation-induced plasticity (TRIP) effect to enhance both the ductility and work-hardening capability of the amorphous matrix. The functionally graded composites with a continuous gradient microstructure were obtained. It was found that the austenitic center possesses good plasticity and toughness. Furthermore, the amorphous surface exhibited high strength and hardness, as well as excellent wear corrosion resistance. Compared with the Ti-6Al-4V alloy, bulk metallic glass composites (BMGCs) exhibit better spontaneous passivation behavior during the potential dynamic polarization. No crystallization was observed on the friction surface, indicating their good friction-reduction and anti-wear properties. Full article

In this study, a porous titanium zirconium (TiZr)-based bulk metallic foam was successfully fabricated using the Cu spacer by employing the hot press method. TiZr-based bulk metallic foams with porosities ranging from 0% to 50% were fabricated and analyzed. The results indicate that thermal conductivity increased with the addition of Cu spacer; the increased thermal conductivity reduced the holding time in the hot press method. Moreover, the compressive strength decreased from 1261 to 76 MPa when the porosity of the TiZr-based bulk metallic foam increased to 50%, and the compressive strength was predictable. In addition, the foam demonstrated favorable biocompatibility in cell viability, cell migration capacity, and calcium deposition tests. Moreover, the pore size of the porous TiZr-based bulk metallic foam was around 120 µm. In conclusion, TiZr-based bulk metallic foam has favorable biocompatibility, mechanical property controllability, and porous structure for bone ingrowth and subsequent enhanced osteointegration. This porous TiZr-based bulk metallic foam has great potential as an orthopedic implant to enhance bone healing and decrease healing time. Full article