Bulk Metallic Glass Plate: Advanced Manufacturing, Structural Properties, And Industrial Applications

Fundamental Composition And Glass-Forming Mechanisms Of Bulk Metallic Glass Plate

Bulk metallic glass plate materials are typically formulated from multi-component alloy systems designed to suppress crystallization during solidification. The most widely studied systems include Zr-based, Fe-based, Ti-based, and precious metal-based (Au, Pt) compositions 91317. For instance, zirconium-rich bulk metallic glasses often comprise quinary alloys containing Zr, Al, Ti, Cu, and Ni, with compositions such as Zr₅₈.₄₇Nb₂.₇₆Cu₁₅.₄Ni₁₂.₆Al₁₀.₃₇ demonstrating high glass-forming ability and critical casting diameters exceeding 5 mm 914. The glass-forming ability is governed by deep eutectic compositions with asymmetric liquidus slopes, which stabilize the supercooled liquid region and delay crystallization 5.

Iron-based bulk metallic glasses, such as Fe₆₈C₁₂B₃Cr₅Mo₁₀W₂, exhibit supercooled liquid regions greater than 50 K and can be cast into amorphous samples with minimum thicknesses of 0.5 mm using chill casting techniques 15. These alloys incorporate refractory metals (Mo, W, Nb) and metalloid elements (C, B, Si) to enhance thermal stability and suppress intermetallic phase formation during cooling 1315. The critical cooling rate—defined as the minimum rate required to avoid crystallization—ranges from 1 °C/s to over 1000 °C/s depending on alloy composition, with higher glass-forming ability alloys permitting slower cooling and thus larger casting dimensions 116.

Gold-based bulk metallic glass plates, containing at least 45 at% Au along with Ag, Pd, Si, and Ge, are of particular interest for luxury applications due to their high hardness (over twice that of conventional crystalline gold alloys), excellent scratch resistance, and low casting temperatures 11. The absence of long-range atomic order in these materials eliminates grain boundaries, resulting in minimal shrinkage on casting and enabling precision shaping via thermoplastic forming or additive manufacturing 11.

The glass transition temperature (Tg) and the supercooled liquid region (ΔTx = Tx - Tg, where Tx is the crystallization onset temperature) are critical parameters governing processability. For example, Zr-Nb-Cu-Ni-Al bulk metallic glasses with optimized Nb/Zr ratios (b/a < 0.040) and Cu/Ni ratios (c/d < 1.15) exhibit enhanced thermal stability and expanded supercooled liquid regions, rendering them suitable for thermoplastic forming operations at temperatures between Tg and Tx 17. Typical Tg values for Zr-based systems range from 350 °C to 450 °C, while Fe-based systems may exhibit Tg values between 500 °C and 600 °C 1015.

Manufacturing Processes And Dimensional Scalability Of Bulk Metallic Glass Plate

Thermoplastic Forming And Sheet Fabrication

Bulk metallic glass plates are frequently manufactured via thermoplastic forming, wherein feedstock (in the form of powders, foils, or fibers) is heated into the supercooled liquid region and shaped under controlled pressure 147. One innovative approach involves weaving bulk metallic glass fibers into complex designs with desired thickness and fiber orientation, followed by thermoplastic heating to consolidate the weave into continuous sheets 1. This method enables the production of plates with tailored wall thickness and area coverage, overcoming the traditional critical thickness limitation of approximately 0.1 mm for monolithic castings 1.

Another method employs rapid capacitor discharge forming (RCDF), which uses rapid heating to process metallic glass-forming alloy powders or amorphous foils into bulk articles 7. In this technique, a green body is formed by packing metallic glass-forming alloy powder or stacking amorphous foil layers, then rapidly heated to a temperature between Tg and the melting point (Tm), and subsequently cooled below Tg to retain the amorphous structure 7. This process is applicable to both marginal glass-formers and bulk glass-formers, and can produce composite articles containing nanocrystalline phases coated with amorphous material 7.

Template-based manufacturing offers another route for producing bulk metallic glass components with high precision and complex three-dimensional geometries 4. In this process, a template (often 3D-printed from plastic) is embedded in a thermosetting polymer, which is then cured and the template removed to create a mold cavity 4. Bulk metallic glass feedstock is heated into the supercooled liquid region and pressed into the mold cavity, where thermoplastic flow improves contact area and replicates fine surface features 4. After cooling, the thermosetting polymer mold is removed, revealing the finished component 4. This method allows for the inclusion of embedded elements and coatings, and is particularly advantageous for producing parts with intricate geometries and high surface quality 4.

Additive Manufacturing Via Cold Gas Spray

Cold gas spray (CGS) is an emerging additive manufacturing technique for producing bulk metallic glass plates with large dimensions using low glass-forming ability alloys 16. In CGS, heated metallic glass particles are accelerated in a high-velocity gas stream and sprayed through a nozzle onto a substrate, building up layers to form a bulk part 16. The process maintains the Reynolds number of the particles within a pre-established range to ensure proper deposition and bonding without melting the material, thereby preserving the amorphous structure 16. This technique avoids the high residual stresses associated with melt-based processes and can produce bulk parts with critical dimensions exceeding 50 mm and porosities below 5% 16. Fe-Si-B alloys processed via CGS have demonstrated amorphous content greater than 75% by mass, making them suitable for applications in transformer cores and electromagnetic motors 16.

Co-Deformation And Composite Fabrication

Bulk metallic glass plates can also be produced as composites through co-deformation with ductile metals 6. In this method, a bulk metallic glass and a metal (such as aluminum or copper) are co-deformed at a temperature within the supercooled liquid region of the glass, where the glass exhibits high elasticity and strength 6. The resulting composite combines the high strength and hardness of the bulk metallic glass with the ductility and electrical conductivity of the metal, making it ideal for applications requiring both mechanical robustness and electrical performance 6. This process is cost-effective and has been demonstrated to produce materials with improved toughness and formability compared to monolithic bulk metallic glasses 6.

Large-Scale Casting Techniques

For producing large-sized bulk metallic glass plates, advanced casting methods such as inclined angle casting with pressure cooling have been developed 3. In this technique, an alloy material is melted in a furnace with an open upper surface, and the furnace floor is tilted to inject the melt into a forcibly cooled mold 3. Simultaneously, an upper punch is used to apply pressure cooling, accelerating heat extraction and enabling the production of amorphous structures with critical diameters previously unattainable 3. This method, referred to as CAP (Cooling-Assisted Pressure) casting, has been used to fabricate bulk metallic glass plates with critical dimensions exceeding 120 mm while maintaining amorphous content greater than 95% by mass 316.

Mechanical And Physical Properties Of Bulk Metallic Glass Plate

Strength, Hardness, And Elastic Modulus

Bulk metallic glass plates exhibit exceptional mechanical properties due to their amorphous atomic structure. Zirconium-based bulk metallic glasses typically display yield strengths in the range of 1.5 to 2.0 GPa, elastic moduli between 80 and 100 GPa, and Vickers hardness values of 400 to 600 HV 913. These values are significantly higher than those of conventional crystalline alloys with similar compositions. For example, Au-based bulk metallic glasses possess hardness values over twice those of crystalline gold alloys with comparable gold content, conferring excellent scratch and wear resistance 11.

Iron-based bulk metallic glass plates, such as those in the Fe-Cr-Mo-C-B system, exhibit yield strengths exceeding 2.5 GPa and elastic moduli around 150 GPa, making them suitable for high-stress structural applications 1015. The high elastic limit (typically 2% strain) allows bulk metallic glass plates to undergo significant elastic deformation before yielding, which is advantageous in applications requiring energy absorption and resilience 12.

Fracture Toughness And Ductility

While bulk metallic glasses are generally brittle in tension, certain compositions and processing methods can enhance fracture toughness and ductility. Zirconium-rich bulk metallic glasses with optimized Ti and Nb content exhibit fracture toughness values (KIC) in the range of 20 to 80 MPa·m^(1/2), comparable to or exceeding those of high-strength steels 9. Composite bulk metallic glasses, such as Zr-based alloys reinforced with graphite particles or ductile metal phases, demonstrate improved plasticity and toughness 26. For instance, a Zr-based bulk metallic glass/graphite composite with a carbide surface layer on the graphite particles exhibits high plasticity, high yield strength, good elasticity, and a low coefficient of friction, making it suitable for applications such as joints, frictional bearings, and springs 2.

Bulk metallic glass-based macroscale compliant mechanisms, fabricated from Ti-Zr alloys with thicknesses of 0.5 mm or greater, have been shown to survive fatigue tests exceeding 1000 cycles under bending loading at an applied stress-to-ultimate strength ratio of 0.25, demonstrating improved fatigue resistance and toughness 12.

Thermal Stability And Glass Transition Behavior

The thermal stability of bulk metallic glass plates is characterized by the glass transition temperature (Tg), the crystallization onset temperature (Tx), and the supercooled liquid region (ΔTx). Zr-Nb-Cu-Ni-Al bulk metallic glasses with high thermal stability exhibit Tg values around 400 °C, Tx values around 480 °C, and ΔTx values exceeding 80 K, providing a wide processing window for thermoplastic forming 17. Fe-based bulk metallic glasses typically have Tg values between 500 °C and 600 °C and ΔTx values greater than 50 K, enabling thermoplastic processing at elevated temperatures 15.

The thermal stability of bulk metallic glass plates can be further enhanced by optimizing alloy composition to suppress intermetallic phase formation and increase the resistance to crystallization 1314. For example, fractional variations in the concentrations of alloying elements in Zr-based systems can stabilize the amorphous phase relative to competing crystalline phases, thereby improving glass-forming ability and thermal stability 14.

Corrosion And Wear Resistance

Bulk metallic glass plates exhibit superior corrosion resistance compared to conventional crystalline alloys due to the absence of grain boundaries and the formation of passive oxide layers 911. Zirconium-based bulk metallic glasses demonstrate excellent resistance to pitting corrosion in chloride-containing environments, with corrosion rates lower than 0.01 mm/year in 3.5% NaCl solution at room temperature 9. Gold-based bulk metallic glasses show high tarnish resistance, maintaining their luster and surface quality even after prolonged exposure to humid and sulfur-containing atmospheres 11.

The wear resistance of bulk metallic glass plates is also exceptional, with wear rates typically one to two orders of magnitude lower than those of crystalline alloys under similar testing conditions 2. The low coefficient of friction (typically 0.1 to 0.3) and high hardness of bulk metallic glass/graphite composites make them particularly suitable for tribological applications such as bearings and sliding contacts 2.

Applications Of Bulk Metallic Glass Plate Across Industries

Aerospace And Defense Applications

Bulk metallic glass plates are increasingly used in aerospace and defense applications due to their high strength-to-weight ratios, excellent fatigue resistance, and ability to be formed into complex geometries 312. Macroscale compliant mechanisms fabricated from Ti-Zr bulk metallic glass plates with thicknesses of 0.5 mm or greater have been demonstrated in applications requiring high cycle fatigue performance, such as flexures, hinges, and energy-absorbing structures 12. The high elastic limit and low density of these materials make them ideal for weight-sensitive aerospace components.

Bulk metallic glass plates are also being explored for use in solid oxide fuel cells (SOFCs) for aircraft power systems 10. In this application, separator plates made from Fe-Cr-Mo-C-B based bulk metallic glass are used to define anode and cathode flow channels and provide electrical interconnection between fuel cell layers 10. The bulk metallic glass material is partially crystallized to enhance electrical conductivity while retaining corrosion resistance and mechanical strength 10. Thermoplastic flow of the bulk metallic glass during assembly improves contact area with adjacent support layers, reducing interfacial resistance and enhancing fuel cell performance 10. The glass transition temperature of the bulk metallic glass is below 600 °C, enabling processing at temperatures compatible with SOFC operating conditions 10.

Electronics And Electrical Engineering

Bulk metallic glass plates are employed in electronics and electrical engineering for applications requiring high electrical conductivity, thermal stability, and mechanical robustness 58. Bulk metallic glass solder materials, formed from alloys with deep eutectics and asymmetric liquidus slopes, exhibit higher strength and elastic modulus than conventional crystalline solders, reducing the risk of damage to fragile low-k interlayer dielectric (ILD) materials due to thermal stress from coefficient of thermal expansion (CTE) mismatch 5. These solder materials can physically, electrically, and thermally couple electronic components to printed circuit boards or integrated heat sinks to semiconductor devices 5. Many bulk metallic glass solder formulations are lead-free, complying with environmental regulations while providing superior performance compared to tin-silver-copper solders 5.

Aluminum-based bulk metallic glass plates with misch metal (MM) additions, expressed as AlTMxMMz (where TM represents transition metals such as Ni, Cu, or Fe, and 0 < x, z < 30 at%), are used in conductive paste compositions for electronic applications 8. These materials exhibit improved metallic glass formation and electrical conductivity, making them suitable for use in printed electronics, flexible circuits, and electromagnetic shielding 8.

Automotive Interior And Structural Components

In the automotive industry, bulk metallic glass plates are utilized for interior components and structural parts requiring high strength, wear resistance, and aesthetic appeal 16. Bulk metallic glass/metal composites produced by co-deformation exhibit a combination of high strength, ductility, and electrical conductivity, making them suitable for applications such as dashboard supports, seat frames, and electrical connectors 6. The materials can withstand operating temperatures ranging from -40 °C to 120 °C, ensuring stability and durability in automotive environments 1.

The low coefficient of friction and high wear resistance of bulk metallic glass/graphite composites make them ideal for automotive bearings, bushings, and sliding contacts 2. These materials reduce maintenance requirements and extend component lifetimes, contributing to improved vehicle reliability and reduced lifecycle costs.

Luxury Goods And Consumer Products

Gold-based bulk metallic glass plates are highly valued in the luxury goods sector for applications such as jewelry, watch cases, and decorative items 11. The high hardness and scratch resistance of these materials, combined with their ability to be cast at low temperatures and shaped like plastics, enable the production of intricate designs with excellent surface finish 11. The high tarnish resistance of Au-based bulk metallic glasses ensures that products maintain their luster and appearance over time, even in challenging environmental conditions 11.

The minimal shrinkage on casting and the ability to replicate fine surface features make bulk metallic glass plates suitable for additive manufacturing and precision molding of luxury goods 411. Coatings can be applied to templates or mold cavities to further enhance surface quality and electrical properties of the final products 4.

Industrial Tooling And Wear-Resistant Components

Bulk metallic glass plates are employed