Research Terms
Keywords
Alloy Design Computational Materials Design Computational Materials Science Failure Analysis Kineticxs Materials Design Materials Selection Medical Devices Metallurgy Thermodynamics
Industries
Aerospace Products and Parts Manufacturing Warfare & Weapons Nuclear Energy Biotech Medical Devices Manufacturing Engineering Processing
This metal matrix composite is a heat-respondent, self-repairing alloy that repairs stress and fatigue cracks without needing skilled technicians and direct access. Metallic materials, such as aluminum alloys, are used in both the structural and non-structural parts of aircraft, such as the fuselage skin, frames, ribs, wing spars, fuel tanks, landing gears, wheel wells, fuel lines, shock struts, cargo doors, floor beams, seat tracks, and more. Although some properties of aluminum, such as cost and weight, are desirable for aerospace and other lightweight material applications, during operation the materials can be subjected to physical stresses due to cyclic loading, resulting in the formation of fatigue cracks, and subsequently, oftentimes fatigue failure. Repairing fatigue cracks typically requires additional materials, direct access to the crack, and the skilled application of a repair technique. In certain cases, engineers decide to replace entire components with fatigue cracks rather than repair the cracks. These cumbersome procedures are not desirable in aerospace application. Additionally, these available techniques pose challenges with regard to bonding and surface preparation.
Researchers at the University of Florida have created a self-healing, heat-respondent metal matrix composite that does not require additional materials, direct access, or skilled application. The repair bonds made by this composite are also significantly stronger than that of available technology, enhancing the performance, reliability, and success of the repaired material.
Composite capable of self-repairing large-scale cracks that have developed during the component’s service life
This matrix composite is comprised of an aluminum-silicon-based alloy that is reinforced with shape memory elements (SMA) for self-repair and damage mitigation. When a crack is present in the matrix material, local stresses induce phase transformations in the SMA reinforcements, causing the SMA reinforcements to stretch and bridge the crack. The cracks are forced closed when the material is heated above the reversion temperature of the SMA reinforcements. While suspended at the reversion temperature, the low melting phase of the matrix partially liquefies and acts as a healing agent by filling into the crack and then solidifying when returned to room temperature. This is a two-step crack repair method; SMA reinforcements force crack closure, and liquefaction of the matrix enables crack repair. Both steps are accomplished by heating the crack area to a pre-determined temperature.
This nickel-titanium (NiTi)-based, precipitation-strengthened shape memory alloy enables production of more efficient, longer-lasting aircraft parts that can withstand higher temperatures. As aerospace, automotive, and power generation technologies advance, there is an increasing need for high-temperature shape memory alloys that allow aircraft to operate under more strenuous conditions than they could previously endure. The aerospace manufacturing industry is worth more than $180 billion and is expected to grow 4 percent in the next 5 years. University of Florida researchers have developed a shape memory alloy that demonstrates longer fatigue life, improved strength and output stress, and increased transformation temperature. This technology can be used for smart, multifunctional aerospace applications including variable geometry chevrons, variable area fan nozzles, and reconfigurable rotor blades.
Nickel-titanium shape memory alloy for aerospace, automotive, and power generation
High-temperature shape memory alloys provide more versatility in the operation of aerospace, automotive, and power generation technologies. This alloy microstructure consists of a nickel-titanium matrix with hafnium and aluminum additions, strengthened by Heusler nanoprecipitates. The hafnium addition to nickel-titanium increases the transformation temperatures, while the aluminum addition allows for the precipitation of the strengthening phase.
This approach to nanoparticle production uses a magnetic processing technique that utilizes cavitation and in-situ particle synthesis, producing metal alloy nanoparticles useful for industrial applications. In recent years, scientists observed how nanoparticles exhibit behaviors advantageous to industrial applications, such as quantum dots and catalysis. Nanotechnology is considerably improving many technology and industry sectors, including information technology, energy and medicine. However, nanoparticle synthesis can be challenging due to the unusually high surface-to-volume ratio of the particles. Available inorganic nanoparticles are produced by methods with drawbacks such as limited availability of precursors, instability, and lack of safety and efficacy. University of Florida researchers have developed an approach to nanoparticle production using cavitation and in-situ particle formation. This approach circumnavigates the lack of various nanoparticle chemistries by producing nanoparticles in-situ by the reaction of an ex-situ particle and the containment vessel. The addition of cavitation enhances this particle formation by enhancing the particles’ wettability potential, thereby decreasing the amount of time required for the particles to separate on the surface of the containment vessel. This approach would be applicable to the production of steel-carbon-magnesium reaction products for subsequent use or for immediate incorporation into a composite.
Nanoparticle production for industrial purposes
This magneto-acoustic processing approach involves a container of metal or ferromagnetic solid combined with abrasive particles in a static magnetic field. The magnetic field is a force field created by a magnet emitting a steady flow of charges. The container inside the magnetic field is surrounded by an induction coil that, when heated up by an electric current, causes the metallic or ferromagnetic solid to become a fluid. This arrangement of the induction coil in accordance with the magnetic field generates sound energy to produce acoustic cavitation and abrasion between the abrasive particles and the container. Acoustic cavitation is the growth and collapse of preexisting bubbles under the influence of ultrasonic fields in liquids. The bubbles collapse in the liquid results in an enormous concentration of energy from the conversion of the kinetic energy of liquid motion into heating of the contents of the bubble. This produces nanoparticles that comprise elements from the container, the metal or ferromagnetic solid, and the abrasive particles. Unlike other particle synthesis techniques, this uses in-situ particle formation, which prevents particle agglomeration while maintaining a good spatial distribution.
These low-cost, lightweight quaternary alloys of Al-Fe-Si enriched with manganese, nickel, cobalt, copper, or zinc have excellent strength and high-temperature tolerance. Companies in the transportation industry are constantly in search of lightweight materials able to withstand high temperatures that could reduce vehicle weight for better fuel efficiency. Just a 10 percent reduction in vehicle mass increases fuel efficiency by 8 percent. An aluminum-iron-silicon alloy is of interest due to its low density, strength, and low cost.
Researchers at the University of Florida have developed Al-Fe-Si alloys with quaternary alloy additions that stabilize the Al-Fe-Si in a phase optimal for 3D printing and high temperature systems.
Low-cost, lightweight quaternary alloys of Al-Fe-Si that are suitable for use in additive manufacturing and that exhibit excellent high-temperature mechanical performance
The quaternary alloys consist of the Al-Fe-Si alloy system enriched with manganese, nickel, cobalt, copper, or zinc. The τ11 phase of the Al-Fe-Si alloy has useful properties such as low density and corrosion resistance, but the phase has a small compositional range. An additional fourth metallic element stabilizes the Al-Fe-Si system by expanding the τ11 phase boundary.
These nontoxic biomedical implants stabilize fractures or temporarily assist the healing of damaged bone. The body safely absorbs these devices once they are no longer needed. Composed of a magnesium alloy that contains calcium and strontium, these implants not only mimic natural bone's mechanical properties, but also promote osteoblast cell function to speed recovery times. When certain orthopedic problems do not respond to conservative treatment, surgical implants can reduce pain and increase mobility. In developed countries, an aging population and increasing obesity rates fuel the need for more of these types of surgical interventions. Forecasts project the global orthopedic implants market to reach $6.2 billion by 2024. Researchers at the University of Florida have developed nontoxic implants that dissolve completely once the body has repaired itself. The implants also promote faster healing times and decreased risk to healthy bone tissue from "stress shielding," where overly rigid implants absorb the stress that bones need to retain their strength.
Nontoxic magnesium alloy implants that stabilize fractures and promote new bone growth before dissolving
University of Florida researchers have invented a nontoxic magnesium alloy for biomedical applications that contains smaller amounts of calcium and strontium. While pure magnesium’s softness causes premature degradation, adding too much calcium or strontium leads to an overly rigid implant. Careful design has resulted in a final product that accurately mimics real bone tissue’s mechanical properties.
These magnesium alloys are designed for use where lightweight and high-strength are crucial, such as in airplanes, automobiles, and space craft. Magnesium alloys have a wide range of applications because they have a low density and have high specific strength and stiffness. The market for magnesium alloys should reach $4.2 billion by 2028. However, the relatively low toughness of these alloys has limited their use in automotive and aerospace applications in the past.
Researchers at the University of Florida have developed a family of magnesium-based alloys for use in automotive and aero applications that maintain the beneficial properties of conventional magnesium alloys but have greatly improved toughness and strength-to-weight ratio.
Light, strong, and tough structural magnesium alloys for automotive, space, and aviation
This family of magnesium alloys contains small percentages of lithium, gallium, or indium. Unlike conventional precipitation-strengthened magnesium-based alloys, these alloys have a body-centered cubic matrix, contributing to their increased toughness.
This nickel-titanium-tin shape memory alloy is a robust combination capable of responding quickly and efficiently to changes in temperature ranging from 150°C to 900°C while maintaining a high specific strength. As advanced aerospace and industrial technologies increasingly use shape memory alloys in actuator systems, the need for high-temperature alloys becomes apparent. Standard alloys have neither sufficient operating temperatures nor specific power to adequately act as actuating systems. University of Florida researchers have developed a shape memory alloy that allows for an increased transformation temperature and higher specific strength compared to standard nickel-alloys. This improvement allows for higher power efficiency within the alloy and an increased operating temperature for actuating applications, and can be used in devices that require small-scale actuator systems. The shape memory alloy can be used in aerospace systems as well as in the body, such as in orthodontic systems or in MEMS devices.
High-temperature shape memory systems for aerospace, automotive, and aeronautical actuating applications
High-temperature shape memory alloys provide more adaptability in the operation of aerospace air foils, MEMS devices, and orthodontic systems. The alloy microstructure comprises a nickel-titanium (NiTi) matrix with a metalloid addition where at least one metalloid added is tin (Sn). The metalloid addition of Sn to NiTi increases the specific strength and transformation temperatures. This addition results in increased alloy strength as well as high operating temperatures.
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