Phys.org April 22, 2024 Refractory alloys are very resistant to heat and wear but are not ductile or resistant to fracture. A team of researchers in the US (UC Berkeley, Lawrence Berkeley National Laboratory, UC Irvine, Pacific Northwest National Laboratory) examined the strength and fracture toughness of the Single-phase body-centered cubic (bcc) refractory alloy, NbTaTiHf, from 77 to 1473 kelvin. Whereas the glide and intersection of screw and mixed dislocations promoted strain hardening controlling uniform deformation, the coordinated slip of <111> edge dislocations with {110} and {112} glide planes prolonged nonuniform strain through formation of kink bands. These bands suppressed […]
Tag Archives: Alloys
Some alloys don’t change size when heated, and we now know why
Phys.org July 31, 2023 The low thermal expansion of Fe–Ni Invar has long been associated with magnetism, but to date, the microscopic underpinnings of the Invar behaviour have eluded both theory and experiment. An international team of researchers (USA – Caltech, Boston College, Argonne National Laboratory, Israel) applied thermodynamic Maxwell relation to nuclear resonant X-ray scattering measurements of the phonon and magnetic entropies under pressure to obtain the separate phonon and magnetic contributions to thermal expansion. They found that the Invar behaviour stems from a competition between phonons and spins. In particular, the phonon contribution to thermal expansion cancelled the […]
Treatment creates steel alloys with superior strength and plasticity
Science Daily June 14, 2023 Nanostructured metallic materials with abundant high-angle grain boundaries exhibit high strength and good radiation resistance. While the nanoscale grains induce high strength, they also degrade tensile ductility. A team of researchers in the US (Purdue University, Sandia National Laboratory) showed that a gradient nanostructured ferritic steel exhibited simultaneous improvement in yield strength by 36% and uniform elongation by 50% compared to the homogenously structured counterpart. In situ tension studies coupled with electron backscattered diffraction analyses revealed intricate coordinated deformation mechanisms in the gradient structures. The outermost nanolaminate grains sustained a substantial plastic strain via a […]
Improving alloys: Researchers successfully establish a strong mechanical bond of immiscible iron and magnesium
Phys.org April 17, 2023 Steel is heavy, and scientists are turning to alternatives in the quest to improve the safety and speed of transportation, while simultaneously lessening its environmental footprint. Joining of Mg alloy to steel has received wide attention for design of multi-materials. Researchers in Japan have described joining of immiscible pure iron and pure magnesium (Fe–Mg), as a simplified model, performed by solid metal dealloying (SMD) between Mg and Fe100−xNix interlayers that were preliminary joined to the Fe part by diffusion bonding. SMD formed an Fe–Mg bicontinuous composite with interconnected morphology at the Fe–Mg weld interface. The effect […]
Shape memory achieved for nano-sized objects
Phys.org March 9, 2023 Magnetoelectric (ME) oxide materials can convert magnetic input into electric output and vice versa, making them excellent candidates for advanced sensing, data storage, and communication. However, their application has been limited to rigid devices due to their brittle nature. An international team of researcher (Switzerland, Germany, South Korea, Spain) has developed flexible ME oxide composite (BaTiO3/CoFe2O4) thin film nanostructures with distinct ME coupling coefficients. In contrast to rigid bulk counterparts, these ceramic nanostructures displayed a flexible behavior after being released from the substrate, and could be transferred onto a stretchable substrate such as polydimethylsiloxane. These ceramic […]
A counterintuitive way to make stronger alloys
Phys.org February 9, 2023 Low-temperature decomposition of supersaturated solid solution into unfavorable intergranular precipitates is a long-standing bottleneck limiting the practical applications of nanograined aluminum alloys that are prepared by severe plastic deformation. Minimizing the vacancy concentration is generally regarded as an effective approach in suppressing the decomposition process. An international team of researchers (China, Norway, Italy) has developed a strategy to stabilize supersaturated solid solution in nanograined Al-Cu alloys via high-density vacancies in combination with Sc microalloying. By generating a two orders of magnitude higher concentration of vacancies bonded in strong (Cu, Sc, vacancy)-rich atomic complexes, a high thermal […]
New strategy to effectively prevent component failures in metals
Phys.org November 11, 2022 Eliminating grain boundaries (GBs) is a primary approach to resisting high-temperature creep in metals which is responsible for component failures at high temperatures. Researchers in China found that grain boundaries in the nanograined single-phased alloy could be effectively stabilized through structural relaxation, and the creep performance of the alloy could be significantly enhanced at elevated temperatures. They demonstrated a creep resistance, with creep rates of ~10–7 per second under gigapascal stress at 700°C (~61% melting point), outperforming that of conventional superalloys. They plan to extend this principle to other engineering alloy families for high-temperature applications, including […]