#intermetallic compounds

Scientists at the U.S. Department of Energy's Ames Laboratory have discovered an earlier unknown discontinuous magnetoelastic transition in a rare-earth intermetallic. The mechanism of the material's changing magnetic state is so unusual, it provides new possibilities for discovery of similar materials.

Materials that possess magnetoelastic phase transitions are highly sought after for a number of developing technologies, including caloric heating and cooling systems. Materials that display this property are rare, and are thought to be exclusively transition metal-based.

But the Ames Laboratory research group found that a rare earth compound made of Europium and Indium, Eu2In, displayed a startlingly sharp magnetic phase transition accompanied with a giant magnetocaloric effect (change in temperature) and no hysteresis.

"This was a very surprising result and one of the least expected places to find such a phenomenon," said Yaroslav Mudryk, an Ames Laboratory scientist. "So this represents the first example of what potentially may become a new class of materials."

Team uses severe deformation method on bulk magnetic alloys for high performance

In a collaborative study involving Equal Channel Angular Extrusion (ECAE), a unique severe plastic deformation (SPD) process, researchers Dr. Ibrahim Karaman from Texas A&M University and Drs. Don Susan and Andrew Kustas of Sandia National Laboratories were able to improve the mechanical properties of magnetic alloys without changing their magnetic properties through microstructural refinement. This process has proven to be troublesome in the past.

Production of high-performance magnetic alloys and other intermetallics could prove particularly useful in aerospace and space exploration where materials must endure harsh environments including temperature extremes, shock, and vibration.

ECAE forces a bar of metallic or polymeric material at a 90-degree angle through a die channel. This process induces SPD without any changes in the cross-sectional area of the sample.

Originally the researchers at Sandia National Laboratories and Texas A&M worked together on a different topic involving shape memory alloys. They quickly realized the potential in combining the strengths of their respective facilities on an entirely new study and subsequently applied the experiences to magnetic alloys.

Nuclear techniques unlock the structure of a rare type of superconducting intermetallic alloy

Nuclear techniques have played an important role in determining the crystal structure of a rare type of intermetallic alloy that exhibits superconductivity.

The research, which was recently published in the Accounts of Chemical Research, was a undertaking led by researchers from the Max Planck Institute for Chemical Physics of Solids, with the collaboration of the Ivan-Franko National University of Lviv, the Technical University Freiberg, the Helmholtz-Zentrum Dresden-Rossendorf, and ANSTO.

Complex metallic alloys (CMAs) have the potential to act as catalysts and serve as materials for devices that covert heat into energy (thermoelectric generators) or use magnetic refrigeration to improve the energy efficiency of cooling and temperature control systems.

Thermoelectric generators are used for low power remote applications or where bulkier but more efficient heat engines would not be possible.

The unique properties of CMAs stem from their intricate superstructure, with each repeating unit cell comprising hundreds or thousands of atoms.

The difference in electrode potential is much less because the touching metals are no longer dissimilar; steel and aluminium only touch the intermetal, and not each other. There will still be regular oxidisation of both materials, but the intermetal should only show aluminium oxidisation because it has a higher potential. Unless zinc is present in the intermetal, in which case that will oxidise first and create a nice barrier like it does with stainless steel.

Yes! So the friction stir process between aluminum and steel results I. The formation of intermetallics (one of the challenges with FeAl alloys). However, here, they actually inhibit corrosion by decoupling the galvanic cell behavior. Knowing one of the authors, there is ongoing work on the corrosion evaluation of these joints.

Researchers discover super-elastic shape-memory material

UConn materials science and engineering researcher Seok-Woo Lee and his colleagues have discovered super-elastic shape-memory properties in a material that could be applied for use as an actuator in the harshest of conditions, such as outer space, and might be the first in a whole new class of shape-memory materials.

If you have ever had braces or wear eyeglasses, you may have already come in contact with shape-memory materials. With applications in a wide range of consumer products such as "unbreakable" frames for glasses, and civil industrial structures like bridges, materials with shape-memory properties can return to their original shape by magnetic forces or heat even after being significantly deformed.

Lee, who is Pratt & Whitney assistant professor of materials science and engineering, studied calcium iron arsenide, or CaFe2As2, which is an intermetallic better known for its novel superconducting properties. Since the material is commonly used in high-temperature superconductors, extensive research had already examined the compound's superconducting and magnetic properties. Inspired by previous research conducted at the U.S Department of Energy's Ames Laboratory by Paul Canfield on calcium iron arsenide's electronic properties, Lee set out to measure the material's high degree of pressure and strain sensitivity for potential applications as a structural material.

Scientists discover superconductor with bounce

The U.S. Department of Energy's Ames Laboratory has discovered extreme "bounce," or super-elastic shape-memory properties in a material that could be applied for use as an actuator in the harshest of conditions, such as outer space, and might be the first in a whole new class of shape memory materials.

Shape-memory materials "remember" their original shape and return to it after they are deformed. They are commonly metallic alloys that make possible "unbreakable" eyeglass frames and quieter jet engines.

But the material in this research, CaFe2As2, is not a metallic alloy but an intermetallic more well-known for its novel superconducting properties. It has been so extensively studied that the team of researchers, from Ames Laboratory and the University of Connecticut, also made note of its high degree of pressure and strain sensitivity, and wondered about its possibilities as a structural material.

Superconductivity research reveals potential new state of matter

Common phenomenon could be key to understanding mechanism of unconventional superconductivity

A potential new state of matter is being reported in the journal Nature, with research showing that among superconducting materials in high magnetic fields, the phenomenon of electronic symmetry breaking is common. The ability to find similarities and differences among classes of materials with phenomena such as this helps researchers establish the essential ingredients that cause novel functionalities such as superconductivity.

The high-magnetic-field state of the heavy fermion superconductor CeRhIn5 revealed a so-called electronic nematic state, in which the material's electrons aligned in a way to reduce the symmetry of the original crystal, something that now appears to be universal among unconventional superconductors. Unconventional superconductivity develops near a phase boundary separating magnetically ordered and magnetically disordered phases of a material.

"The appearance of the electronic alignment, called nematic behavior, in a prototypical heavy-fermion superconductor highlights the interrelation of nematicity and unconventional superconductivity, suggesting nematicity to be common among correlated superconducting materials," said Filip Ronning of Los Alamos National Laboratory, lead author on the paper. Heavy fermions are intermetallic compounds, containing rare earth or actinide elements.