The influence of alloying on the stacking fault energy of gold from density functional theory calculations

中熵稀土合金中压力诱导的堆垛无序与长程Sm型有序的抑制

Pressure-Induced Stacking Disorder and Suppression of Long-Range Sm-type Order in Medium-Entropy Rare-Earth Alloys

该研究通过同步辐射X射线衍射发现，中熵稀土合金TbHoEr和TbHoDy在压力下跳过Sm型中间相，经堆垛无序的密堆积态转变，揭示中熵合金化可改变稀土材料的压力诱导堆垛路径。

Hydride growth mechanism in Zircaloy-4: investigation of the partitioning of alloying elements

The long-term safety of water-based nuclear reactors relies in part on the reliability of zirconium-based nuclear fuel. Yet the progressive ingress of hydrogen during service makes zirconium alloys subject to delayed hydride cracking. Here, we use a combination of electron back-scattered diffraction and atom probe tomography to investigate specific microstructural features from the as-received sample and in the blocky-alpha microstructure, before and after electrochemical charging with hydrogen or deuterium followed by a low temperature heat treatment at 400C for 5 hours followed by furnace co…

Understanding the mechanical properties of reduced activation steels

Reduced activation ferritic/martensitic (RAFM) steels are structural materials with potential application in Generation-IV fission and fusion reactors. We use density-functional theory to scrutinize the micro-mechanical properties of the main alloy phases of three RAFM steels based on the body-centered cubic FeCrWVMn solid solution. We assess the lattice parameters and elastic properties of ferromagnetic $α$-Fe and Fe$_{91}$Cr$_{9}$, which are the main building blocks of the RAFM steels, and present a detailed analysis of the calculated alloying effects of V, Cr, Mn, and W on the mechanical pr…

Goldene 如何堆叠？

How does Goldene Stack?

本文利用密度泛函理论计算揭示了多层 Goldene 的堆叠演化规律：六层以内保持 AA 型堆叠，七层时自发转变为块体金 FCC 结构，并发现量子限域导致单层与多层 Goldene 在 Dirac 锥数量及光学吸收各向异性上的显著差异。

Origins and dissociation of pyramidal <c + a> dislocations in magnesium and its alloys

Alloying magnesium (Mg) with rare earth elements such as yttrium (Y) has been reported to activate the pyramidal <c + a> slip systems and improve the plasticity of Mg at room temperature. However, the origins of such dislocations and their dissociation mechanisms remain poorly understood. Here, we systematically investigate these mechanisms using dispersion-inclusive density functional theory, in combination with molecular dynamics simulations. We find that <c + a> dislocations form more readily on the pyramidal I plane than on the pyramidal II plane in Mg. The addition of Y atoms in Mg facili…

从高熵合金到具有高熵的合金：材料科学与工程中推动可持续冶金发展的新范式

From High-Entropy Alloys to Alloys with High Entropy: A New Paradigm in Materials Science and Engineering for Advancing Sustainable Metallurgy

本研究提出从高熵合金到高熵型合金的设计新范式，突破传统单一主金属设计思路，引入多元素无主成分理念，结合多组分废料利用与AI建模工具，推动可持续冶金发展。

Stacking fault energy induced softening in the nucleation limited plasticity regime: a molecular dynamics study on Cu-Al alloys

In general, with the addition of solutes, the yield strength of alloys is expected to increase and this phenomenon is known as solid solution strengthening. However, reports on the ``anomalous'' softening with alloying additions are not uncommon; for example, it is known that the heterogeneous nucleation of dislocations at the sites of solute atoms can lead to softening. In this study, using Molecular Dynamics (MD) simulations, we show anomalous softening in Cu-Al alloys deformed at 300 K; specifically, not only the yield stress but also the magnitude of stress drop at yield decrease with incr…

Optical vibrations of hydrogen in disordered palladium-gold alloys

In the fcc lattice of Pd, hydrogen occupies octahedral interstitial positions with cubic symmetry. One could therefore expect that in dilute solid H solutions in Pd the fundamental band of optical H vibrations should be reduced to a narrow line of 3-fold degenerate, non-interacting isotropic local oscillators. A few attempts to test this assumption by inelastic neutron scattering gave ambiguous results due to the very small limiting hydrogen concentration, x<0.001, of the PdH$_x$ solutions at low temperatures. We increased maximum x by alloying Pd with 20 at% Au and studied disordered Pd$_{0.8…

MEAM potentials for Al, Si, Mg, Cu, and Fe alloys

A set of Modified Embedded Atom Method (MEAM) potentials for the interactions between Al, Si, Mg, Cu, and Fe was developed from a combination of each element's MEAM potential in order to study metal alloying. Previously published MEAM parameters of single elements have been improved for better agreement to the generalized stacking fault energy (GSFE) curves when compared with ab-initio generated GSFE curves. The MEAM parameters for element pairs were constructed based on the structural and elastic properties of element pairs in the NaCl reference structure garnered from ab-initio calculations,…

Creep properties and deformation mechanisms of single-crystalline $γ^\prime$-strengthened superalloys in dependence of the Co/Ni ratio

Co-base superalloys are considered as promising high temperature materials besides the well-established Ni-base superalloys. However, Ni appears to be an indispensable alloying element also in Co-base superalloys. To address the influence of the base elements on the deformation behavior, high-temperature compressive creep experiments were performed on a single crystal alloy series that was designed to exhibit a varying Co/Ni ratio and a constant Al, W and Cr content. Creep tests were performed at 900 °C and 250 MPa and the resulting microstructures and defect configurations were characterized …

Vapor-liquid-solid growth of highly-mismatched semiconductor nanowires with high-fidelity van der Waals layer stacking

Nanobelts, nanoribbons and other quasi-one-dimensional nanostructures formed from layered, so-called, van der Waals semiconductors have garnered much attention due to their high-performance, tunable optoelectronic properties. For layered alloys made from the gallium monochalcogenides GaS, GaSe, and GaTe, near-continuous tuning of the energy bandgap across the full composition range has been achieved in GaSe1-xSx and GaSe1-xTex alloys. Gold-catalyzed vapor-liquid-solid (VLS) growth of these alloys yields predominantly nanobelts, nanoribbons and other nanostructures for which the fast crystal gr…

Spontaneous polarization induced doping in quasi-free standing epitaxial graphene on silicon carbide from density functional theory

By means of density functional theory (DFT) calculations we have quantitatively estimated the impact of the spontaneous polarization (SP) of the SiC(0001) substrate on the electronic properties of quasi-freestanding graphene (QFG) decoupled from the SiC by H intercalation. To correctly include within standard DFT slab calculations the influence of the SP, which is a bulk property, on a surface confined property such as the graphene's doping, we attach a double gold layer at the C-terminated bottom of the slab which introduces a metal induced gap state that pins the chemical potential within th…