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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Microstructural Progression of Shear-Induced Mixing in a CuNi Alloy

Shear deformation has been highlighted in multiple research efforts for its ability to impart mechanical properties improvements and unique microstructures. When used to process and densify powdered material, these shear-based consolidation techniques are commonly referred to as friction consolidation (FC). In this paper, we have examined the microstructural evolution from compacted Cu and Ni powders to a consolidated Cu0.5Ni0.5 alloy. We have shown various stages of porosity reduction and preferential deformation being accommodated by the more ductile material early in the process, leading to formation of a tortuous microstructural zone. Porosity reduction was extensive, decreasing from ~65% in the unprocessed powder to ~1% in the fully consolidated alloy. The final consolidated alloy showed roughly a 2X hardness improvement over the unalloyed, compacted material. Unique aspects of this work include demonstration of the ability to use FC processing to produce a submicron and equiaxed grain size in samples within a 0.5 to 2 minute processing time.

Overman, Nicole R.↗
DOE OSTI2020

Materials Data on CuNi by Materials Project

NiCu is Magnesium-derived structured and crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. Ni is bonded to six equivalent Ni and six equivalent Cu atoms to form NiCu6Ni6 cuboctahedra that share corners with eighteen equivalent NiCu6Ni6 cuboctahedra, edges with six equivalent NiCu6Ni6 cuboctahedra, edges with twelve equivalent CuCu6Ni6 cuboctahedra, faces with eight equivalent NiCu6Ni6 cuboctahedra, and faces with twelve equivalent CuCu6Ni6 cuboctahedra. All Ni–Ni bond lengths are 2.50 Å. All Ni–Cu bond lengths are 2.53 Å. Cu is bonded to six equivalent Ni and six equivalent Cu atoms to form CuCu6Ni6 cuboctahedra that share corners with eighteen equivalent CuCu6Ni6 cuboctahedra, edges with six equivalent CuCu6Ni6 cuboctahedra, edges with twelve equivalent NiCu6Ni6 cuboctahedra, faces with eight equivalent CuCu6Ni6 cuboctahedra, and faces with twelve equivalent NiCu6Ni6 cuboctahedra. All Cu–Cu bond lengths are 2.50 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La2(CuNi)5 by Materials Project

La2(NiCu)5 crystallizes in the orthorhombic Pmmm space group. The structure is three-dimensional. there are two inequivalent La sites. In the first La site, La is bonded in a 6-coordinate geometry to twelve Ni and six Cu atoms. There are eight shorter (3.22 Å) and four longer (3.23 Å) La–Ni bond lengths. There are two shorter (2.92 Å) and four longer (2.95 Å) La–Cu bond lengths. In the second La site, La is bonded in a 6-coordinate geometry to eight equivalent Ni and ten Cu atoms. All La–Ni bond lengths are 3.23 Å. There are a spread of La–Cu bond distances ranging from 2.93–3.23 Å. There are two inequivalent Ni sites. In the first Ni site, Ni is bonded to four equivalent La, four equivalent Ni, and four equivalent Cu atoms to form NiLa4Cu4Ni4 cuboctahedra that share corners with four equivalent CuLa4Cu4Ni4 cuboctahedra, corners with twelve NiLa4Cu5Ni3 cuboctahedra, edges with ten NiLa4Cu5Ni3 cuboctahedra, and faces with ten NiLa4Cu4Ni4 cuboctahedra. All Ni–Ni bond lengths are 2.53 Å. All Ni–Cu bond lengths are 2.47 Å. In the second Ni site, Ni is bonded to four La, three Ni, and five Cu atoms to form NiLa4Cu5Ni3 cuboctahedra that share corners with two equivalent CuLa4Cu4Ni4 cuboctahedra, corners with fourteen NiLa4Cu4Ni4 cuboctahedra, edges with two equivalent CuLa4Cu4Ni4 cuboctahedra, edges with eight NiLa4Cu4Ni4 cuboctahedra, faces with two equivalent CuLa4Cu4Ni4 cuboctahedra, and faces with eight NiLa4Cu4Ni4 cuboctahedra. There are one shorter (2.54 Å) and one longer (2.57 Å) Ni–Ni bond lengths. There are a spread of Ni–Cu bond distances ranging from 2.46–2.56 Å. There are three inequivalent Cu sites. In the first Cu site, Cu is bonded in a 12-coordinate geometry to three La, four equivalent Ni, and two equivalent Cu atoms. Both Cu–Cu bond lengths are 2.48 Å. In the second Cu site, Cu is bonded in a 12-coordinate geometry to three La and six Ni atoms. In the third Cu site, Cu is bonded to four equivalent La, four equivalent Ni, and four equivalent Cu atoms to form CuLa4Cu4Ni4 cuboctahedra that share corners with four equivalent CuLa4Cu4Ni4 cuboctahedra, corners with twelve NiLa4Cu5Ni3 cuboctahedra, edges with two equivalent CuLa4Cu4Ni4 cuboctahedra, edges with eight equivalent NiLa4Cu5Ni3 cuboctahedra, faces with two equivalent CuLa4Cu4Ni4 cuboctahedra, and faces with eight equivalent NiLa4Cu5Ni3 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuNi by Materials Project

NiCu is Copper-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Ni sites. In the first Ni site, Ni is bonded to six equivalent Ni and six Cu atoms to form NiCu6Ni6 cuboctahedra that share corners with twelve NiCu6Ni6 cuboctahedra, edges with twelve NiCu6Ni6 cuboctahedra, edges with twelve CuCu6Ni6 cuboctahedra, faces with six equivalent NiCu6Ni6 cuboctahedra, and faces with twelve CuCu6Ni6 cuboctahedra. All Ni–Ni bond lengths are 2.50 Å. All Ni–Cu bond lengths are 2.51 Å. In the second Ni site, Ni is bonded to ten equivalent Ni and six Cu atoms to form NiCu6Ni10 cuboctahedra that share corners with ten CuCu6Ni6 cuboctahedra, corners with twelve NiCu6Ni6 cuboctahedra, edges with eight CuCu6Ni6 cuboctahedra, edges with sixteen NiCu6Ni6 cuboctahedra, faces with sixteen equivalent NiCu6Ni10 cuboctahedra, and faces with eighteen CuCu6Ni6 cuboctahedra. There are a spread of Ni–Ni bond distances ranging from 2.50–5.00 Å. All Ni–Cu bond lengths are 2.51 Å. There are three inequivalent Cu sites. In the first Cu site, Cu is bonded to six equivalent Ni and six equivalent Cu atoms to form CuCu6Ni6 cuboctahedra that share corners with twelve CuCu6Ni6 cuboctahedra, edges with twelve equivalent NiCu6Ni6 cuboctahedra, edges with twelve CuCu6Ni6 cuboctahedra, faces with six equivalent CuCu6Ni6 cuboctahedra, and faces with twelve equivalent NiCu6Ni6 cuboctahedra. All Cu–Cu bond lengths are 2.50 Å. In the second Cu site, Cu is bonded to six Ni and six equivalent Cu atoms to form CuCu6Ni6 cuboctahedra that share corners with five equivalent NiCu6Ni10 cuboctahedra, corners with twelve CuCu6Ni6 cuboctahedra, edges with ten NiCu6Ni6 cuboctahedra, edges with twelve CuCu6Ni6 cuboctahedra, faces with six equivalent CuCu6Ni6 cuboctahedra, and faces with fifteen NiCu6Ni6 cuboctahedra. All Cu–Ni bond lengths are 2.51 Å. All Cu–Cu bond lengths are 2.50 Å. In the third Cu site, Cu is bonded to six Ni and six equivalent Cu atoms to form CuCu6Ni6 cuboctahedra that share corners with five equivalent NiCu6Ni10 cuboctahedra, corners with twelve CuCu6Ni6 cuboctahedra, edges with ten NiCu6Ni6 cuboctahedra, edges with twelve CuCu6Ni6 cuboctahedra, faces with six equivalent CuCu6Ni6 cuboctahedra, and faces with fifteen NiCu6Ni6 cuboctahedra. All Cu–Cu bond lengths are 2.50 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce2(CuNi)5 by Materials Project

Ce2(NiCu)5 crystallizes in the orthorhombic Pmmm space group. The structure is three-dimensional. there are two inequivalent Ce sites. In the first Ce site, Ce is bonded in a 6-coordinate geometry to eight equivalent Ni and ten Cu atoms. All Ce–Ni bond lengths are 3.19 Å. There are a spread of Ce–Cu bond distances ranging from 2.88–3.19 Å. In the second Ce site, Ce is bonded in a 6-coordinate geometry to twelve Ni and six Cu atoms. There are eight shorter (3.18 Å) and four longer (3.19 Å) Ce–Ni bond lengths. There are two shorter (2.87 Å) and four longer (2.90 Å) Ce–Cu bond lengths. There are two inequivalent Ni sites. In the first Ni site, Ni is bonded to four equivalent Ce, four equivalent Ni, and four equivalent Cu atoms to form NiCe4Cu4Ni4 cuboctahedra that share corners with four equivalent CuCe4Cu4Ni4 cuboctahedra, corners with twelve NiCe4Cu5Ni3 cuboctahedra, edges with ten NiCe4Cu5Ni3 cuboctahedra, and faces with ten NiCe4Cu4Ni4 cuboctahedra. All Ni–Ni bond lengths are 2.49 Å. All Ni–Cu bond lengths are 2.44 Å. In the second Ni site, Ni is bonded to four Ce, three Ni, and five Cu atoms to form NiCe4Cu5Ni3 cuboctahedra that share corners with two equivalent CuCe4Cu4Ni4 cuboctahedra, corners with fourteen NiCe4Cu4Ni4 cuboctahedra, edges with two equivalent CuCe4Cu4Ni4 cuboctahedra, edges with eight NiCe4Cu4Ni4 cuboctahedra, faces with two equivalent CuCe4Cu4Ni4 cuboctahedra, and faces with eight NiCe4Cu4Ni4 cuboctahedra. There are one shorter (2.50 Å) and one longer (2.53 Å) Ni–Ni bond lengths. There are a spread of Ni–Cu bond distances ranging from 2.44–2.51 Å. There are three inequivalent Cu sites. In the first Cu site, Cu is bonded in a 12-coordinate geometry to three Ce and six Ni atoms. In the second Cu site, Cu is bonded in a 12-coordinate geometry to three Ce, four equivalent Ni, and two equivalent Cu atoms. Both Cu–Cu bond lengths are 2.45 Å. In the third Cu site, Cu is bonded to four equivalent Ce, four equivalent Ni, and four equivalent Cu atoms to form CuCe4Cu4Ni4 cuboctahedra that share corners with four equivalent CuCe4Cu4Ni4 cuboctahedra, corners with twelve NiCe4Cu5Ni3 cuboctahedra, edges with two equivalent CuCe4Cu4Ni4 cuboctahedra, edges with eight equivalent NiCe4Cu5Ni3 cuboctahedra, faces with two equivalent CuCe4Cu4Ni4 cuboctahedra, and faces with eight equivalent NiCe4Cu5Ni3 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CeAl(CuNi)2 by Materials Project

CeAl(NiCu)2 crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. Ce is bonded in a 6-coordinate geometry to six equivalent Ni, eight equivalent Cu, and four equivalent Al atoms. There are two shorter (2.85 Å) and four longer (2.90 Å) Ce–Ni bond lengths. All Ce–Cu bond lengths are 3.21 Å. All Ce–Al bond lengths are 3.27 Å. Ni is bonded in a 12-coordinate geometry to three equivalent Ce, four equivalent Cu, and two equivalent Al atoms. All Ni–Cu bond lengths are 2.52 Å. Both Ni–Al bond lengths are 2.48 Å. Cu is bonded to four equivalent Ce, four equivalent Ni, two equivalent Cu, and two equivalent Al atoms to form a mixture of distorted edge, corner, and face-sharing CuCe4Al2Cu2Ni4 cuboctahedra. Both Cu–Cu bond lengths are 2.55 Å. Both Cu–Al bond lengths are 2.47 Å. Al is bonded in a 12-coordinate geometry to four equivalent Ce, four equivalent Ni, and four equivalent Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CuNi by Materials Project

NiCu crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. Ni is bonded in a 8-coordinate geometry to six equivalent Ni and four equivalent Cu atoms. There are four shorter (2.45 Å) and two longer (2.62 Å) Ni–Ni bond lengths. All Ni–Cu bond lengths are 2.45 Å. Cu is bonded in a 8-coordinate geometry to four equivalent Ni and six equivalent Cu atoms. There are four shorter (2.45 Å) and two longer (2.62 Å) Cu–Cu bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U2(CuNi)5 by Materials Project

U2(NiCu)5 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are two inequivalent U sites. In the first U site, U is bonded in a 1-coordinate geometry to ten Ni and six Cu atoms. There are a spread of U–Ni bond distances ranging from 2.79–3.02 Å. There are four shorter (2.83 Å) and two longer (2.86 Å) U–Cu bond lengths. In the second U site, U is bonded in a 4-coordinate geometry to seven Ni and nine Cu atoms. There are a spread of U–Ni bond distances ranging from 2.80–3.02 Å. There are a spread of U–Cu bond distances ranging from 2.81–2.85 Å. There are five inequivalent Ni sites. In the first Ni site, Ni is bonded to three equivalent U, five Ni, and four Cu atoms to form distorted NiU3Cu4Ni5 cuboctahedra that share corners with four NiU3Cu5Ni4 cuboctahedra, corners with fourteen CuU3Cu3Ni6 cuboctahedra, edges with six equivalent NiU3Cu4Ni5 cuboctahedra, faces with six NiU3Cu5Ni4 cuboctahedra, and faces with twelve CuU3Cu3Ni6 cuboctahedra. There are a spread of Ni–Ni bond distances ranging from 2.44–2.85 Å. There are two shorter (2.39 Å) and two longer (2.41 Å) Ni–Cu bond lengths. In the second Ni site, Ni is bonded to three U, four Ni, and five Cu atoms to form distorted NiU3Cu5Ni4 cuboctahedra that share corners with eight NiU3Cu4Ni5 cuboctahedra, corners with ten CuU3Cu3Ni6 cuboctahedra, edges with six NiU3Cu5Ni4 cuboctahedra, faces with three equivalent NiU3Cu4Ni5 cuboctahedra, and faces with fifteen CuU3Cu3Ni6 cuboctahedra. There are two shorter (2.81 Å) and one longer (2.84 Å) Ni–Ni bond lengths. There are a spread of Ni–Cu bond distances ranging from 2.41–2.43 Å. In the third Ni site, Ni is bonded to three U, four Ni, and five Cu atoms to form distorted NiU3Cu5Ni4 cuboctahedra that share corners with eight NiU3Cu4Ni5 cuboctahedra, corners with ten CuU3Cu3Ni6 cuboctahedra, edges with six NiU3Cu5Ni4 cuboctahedra, faces with three equivalent NiU3Cu4Ni5 cuboctahedra, and faces with fifteen CuU3Cu3Ni6 cuboctahedra. There are two shorter (2.80 Å) and one longer (2.81 Å) Ni–Ni bond lengths. There are a spread of Ni–Cu bond distances ranging from 2.40–2.45 Å. In the fourth Ni site, Ni is bonded in a 4-coordinate geometry to four U, three Ni, and nine Cu atoms. There are a spread of Ni–Cu bond distances ranging from 2.81–2.86 Å. In the fifth Ni site, Ni is bonded in a 4-coordinate geometry to four U, six Ni, and six Cu atoms. There are a spread of Ni–Cu bond distances ranging from 2.80–2.85 Å. There are three inequivalent Cu sites. In the first Cu site, Cu is bonded to three U, six Ni, and three Cu atoms to form distorted CuU3Cu3Ni6 cuboctahedra that share corners with six NiU3Cu4Ni5 cuboctahedra, corners with twelve CuU3Cu3Ni6 cuboctahedra, edges with six CuU3Cu3Ni6 cuboctahedra, faces with nine NiU3Cu4Ni5 cuboctahedra, and faces with nine CuU3Cu3Ni6 cuboctahedra. There are a spread of Cu–Cu bond distances ranging from 2.37–2.40 Å. In the second Cu site, Cu is bonded to three U, six Ni, and three Cu atoms to form distorted CuU3Cu3Ni6 cuboctahedra that share corners with six NiU3Cu4Ni5 cuboctahedra, corners with twelve CuU3Cu3Ni6 cuboctahedra, edges with six CuU3Cu3Ni6 cuboctahedra, faces with nine NiU3Cu4Ni5 cuboctahedra, and faces with nine CuU3Cu3Ni6 cuboctahedra. There are a spread of Cu–Cu bond distances ranging from 2.36–2.43 Å. In the third Cu site, Cu is bonded to three equivalent U, five Ni, and four Cu atoms to form CuU3Cu4Ni5 cuboctahedra that share corners with eight CuU3Cu3Ni6 cuboctahedra, corners with ten NiU3Cu4Ni5 cuboctahedra, edges with six equivalent CuU3Cu4Ni5 cuboctahedra, faces with six NiU3Cu5Ni4 cuboctahedra, and faces with twelve CuU3Cu3Ni6 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CeAl(CuNi)2 by Materials Project

CeAl(NiCu)2 crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Ce is bonded in a 6-coordinate geometry to eight equivalent Ni, seven Cu, and three equivalent Al atoms. There are four shorter (3.22 Å) and four longer (3.28 Å) Ce–Ni bond lengths. There are a spread of Ce–Cu bond distances ranging from 2.94–3.26 Å. There are one shorter (2.95 Å) and two longer (3.00 Å) Ce–Al bond lengths. Ni is bonded to four equivalent Ce, two equivalent Ni, four Cu, and two equivalent Al atoms to form distorted NiCe4Al2Cu4Ni2 cuboctahedra that share corners with eight CuCe3Al3Cu2Ni4 cuboctahedra, corners with twelve equivalent NiCe4Al2Cu4Ni2 cuboctahedra, edges with four equivalent CuCe4Al2Cu2Ni4 cuboctahedra, edges with six equivalent NiCe4Al2Cu4Ni2 cuboctahedra, faces with six equivalent NiCe4Al2Cu4Ni2 cuboctahedra, and faces with ten CuCe3Al3Cu2Ni4 cuboctahedra. There are one shorter (2.58 Å) and one longer (2.60 Å) Ni–Ni bond lengths. There are a spread of Ni–Cu bond distances ranging from 2.48–2.58 Å. Both Ni–Al bond lengths are 2.47 Å. There are two inequivalent Cu sites. In the first Cu site, Cu is bonded to three equivalent Ce, four equivalent Ni, two equivalent Cu, and three equivalent Al atoms to form distorted CuCe3Al3Cu2Ni4 cuboctahedra that share corners with four equivalent CuCe4Al2Cu2Ni4 cuboctahedra, corners with eight equivalent NiCe4Al2Cu4Ni2 cuboctahedra, edges with six equivalent CuCe3Al3Cu2Ni4 cuboctahedra, faces with eight CuCe3Al3Cu2Ni4 cuboctahedra, and faces with twelve equivalent NiCe4Al2Cu4Ni2 cuboctahedra. Both Cu–Cu bond lengths are 2.47 Å. There are two shorter (2.96 Å) and one longer (3.03 Å) Cu–Al bond lengths. In the second Cu site, Cu is bonded to four equivalent Ce, four equivalent Ni, two equivalent Cu, and two equivalent Al atoms to form distorted CuCe4Al2Cu2Ni4 cuboctahedra that share corners with eight equivalent NiCe4Al2Cu4Ni2 cuboctahedra, corners with twelve CuCe3Al3Cu2Ni4 cuboctahedra, edges with two equivalent CuCe4Al2Cu2Ni4 cuboctahedra, edges with eight equivalent NiCe4Al2Cu4Ni2 cuboctahedra, faces with eight equivalent NiCe4Al2Cu4Ni2 cuboctahedra, and faces with eight CuCe3Al3Cu2Ni4 cuboctahedra. Both Cu–Al bond lengths are 2.52 Å. Al is bonded in a 12-coordinate geometry to three equivalent Ce, four equivalent Ni, and five Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu2(CuNi)5 by Materials Project

Eu2(NiCu)5 crystallizes in the orthorhombic Pmmm space group. The structure is three-dimensional. there are two inequivalent Eu sites. In the first Eu site, Eu is bonded in a 6-coordinate geometry to eight equivalent Ni and ten Cu atoms. All Eu–Ni bond lengths are 3.24 Å. There are a spread of Eu–Cu bond distances ranging from 2.93–3.23 Å. In the second Eu site, Eu is bonded in a 6-coordinate geometry to twelve Ni and six Cu atoms. All Eu–Ni bond lengths are 3.23 Å. There are two shorter (2.92 Å) and four longer (2.93 Å) Eu–Cu bond lengths. There are two inequivalent Ni sites. In the first Ni site, Ni is bonded to four equivalent Eu, four equivalent Ni, and four equivalent Cu atoms to form NiEu4Cu4Ni4 cuboctahedra that share corners with four equivalent CuEu4Cu4Ni4 cuboctahedra, corners with twelve NiEu4Cu5Ni3 cuboctahedra, edges with ten NiEu4Cu5Ni3 cuboctahedra, and faces with ten NiEu4Cu4Ni4 cuboctahedra. All Ni–Ni bond lengths are 2.53 Å. All Ni–Cu bond lengths are 2.48 Å. In the second Ni site, Ni is bonded to four Eu, three Ni, and five Cu atoms to form NiEu4Cu5Ni3 cuboctahedra that share corners with two equivalent CuEu4Cu4Ni4 cuboctahedra, corners with fourteen NiEu4Cu4Ni4 cuboctahedra, edges with two equivalent CuEu4Cu4Ni4 cuboctahedra, edges with eight NiEu4Cu4Ni4 cuboctahedra, faces with two equivalent CuEu4Cu4Ni4 cuboctahedra, and faces with eight NiEu4Cu4Ni4 cuboctahedra. There are one shorter (2.53 Å) and one longer (2.54 Å) Ni–Ni bond lengths. There are four shorter (2.48 Å) and one longer (2.54 Å) Ni–Cu bond lengths. There are three inequivalent Cu sites. In the first Cu site, Cu is bonded in a 12-coordinate geometry to three Eu and six Ni atoms. In the second Cu site, Cu is bonded in a 12-coordinate geometry to three Eu, four equivalent Ni, and two equivalent Cu atoms. Both Cu–Cu bond lengths are 2.49 Å. In the third Cu site, Cu is bonded to four equivalent Eu, four equivalent Ni, and four equivalent Cu atoms to form CuEu4Cu4Ni4 cuboctahedra that share corners with four equivalent CuEu4Cu4Ni4 cuboctahedra, corners with twelve NiEu4Cu5Ni3 cuboctahedra, edges with two equivalent CuEu4Cu4Ni4 cuboctahedra, edges with eight equivalent NiEu4Cu5Ni3 cuboctahedra, faces with two equivalent CuEu4Cu4Ni4 cuboctahedra, and faces with eight equivalent NiEu4Cu5Ni3 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Co-sputtered CuNi heteroatomic electrocatalyst for enhanced 5-hydroxymethylfurfural selective electrochemical conversion

The electrochemical conversion of biomass-derived 5-hydroxymethylfurfural (HMF) represents a promising, economically viable, and environmentally sustainable approach for producing value-added chemicals using renewable energy and in situ hydrogen generated through water electrolysis. However, the electrochemical hydrogenation (ECH) of HMF remains challenging due to the inherently low catalytic activity and selectivity of the electrodes, compounded by competition with the kinetically favored hydrogen evolution reaction (HER) in aqueous electrolytes. In this work, we demonstrate that Cu x Ni 100−x heteroatomic thin films, fabricated via direct current (DC) magnetron co-sputtering, achieve a more than one order of magnitude increase in the HMF to 2,5-Bis-hydroxymethylfuran (BHMF) conversion rate, with nearly 50% faradic efficiency (FE) for BHMF, when compared to pure Cu and Ni electrodes (~ 10% BHMF FE). Our results suggest that the synergistic interaction between Cu and Ni creates an optimal catalytic environment for both HMF and adsorbed hydrogen (H ads ) species, thereby enhancing BHMF formation through the ECH pathway.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Synthesis of Core@Shell Cu-Ni@Pt-Cu Nano-Octahedra and Their Improved MOR Activity

Fabrication of 3d metal-based core@shell nanocatalysts with engineered Pt-surfaces provides an effective approach for improving the catalytic performance. The challenges in such preparation include shape control of the 3d metallic cores and thickness control of the Pt-based shells. Herein, we report a colloidal seed-mediated method to prepare octahedral CuNi@Pt-Cu core@shell nanocrystals using CuNi octahedral cores as the template. By precisely controlling the synthesis conditions including the deposition rate and diffusion rate of the shell-formation through tuning the capping ligand, reaction temperature, and heating rate, uniform Pt-based shells can be achieved with a thickness of < 1 nm. Furthermore, the resultant carbon-supported CuNi@Pt-Cu core@shell nano-octahedra showed superior activity in electrochemical methanol oxidation reaction (MOR) compared with the commercial Pt/C catalysts and carbon-supported CuNi@Pt-Cu nano-polyhedron counterparts, demonstrating that both the lattice strain and shape effects arising from the as-prepared CuNi@Pt-Cu octahedral nanocatalysts play a crucial role in MOR performance.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Cu–Ni Oxidation Mechanism Unveiled: A Machine Learning-Accelerated First-Principles and in Situ TEM Study

Here, the development of accurate methods for determining how alloy surfaces spontaneously restructure under reactive and corrosive environments is a key, long-standing, grand challenge in materials science. Using machine learning-accelerated density functional theory and rare-event methods, in conjunction with in situ environmental transmission electron microscopy (ETEM), we examine the interplay between surface reconstructions and preferential segregation tendencies of CuNi(100) surfaces under oxidation conditions. Our modeling approach predicts that oxygen-induced Ni segregation in CuNi alloys favors Cu(100)-O c(2 × 2) reconstruction and destabilizes the Cu(100)-O (2√2 × √2)R45° missing row reconstruction (MRR). In situ ETEM experiments validate these predictions and show Ni segregation followed by NiO nucleation and growth in regions without MRR, with secondary nucleation and growth of Cu 2 O in MRR regions. Our approach based on combining disparate computational components and in situ ETEM provides a holistic description of the oxidation mechanism in CuNi, which applies to other alloy systems.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Community Solar and Community Solar+Storage: A Roadmap of Barriers and Solutions for Commercial Systems in NYC

Sustainable CUNY worked with decision makers and subject matter experts (SME's) to identify the barriers to and solutions for advancing commercial Community Solar (CS) and CS+Storage (CS+S) in urban areas. This roadmap captures the key challenges and solutions identified by New York City (NYC) stakeholders, including the Real Estate Board of New York (REBNY), through a collaborative process. Solar, as well as storage, are among the fastest growing energy segments in the United States, with CS, also known as Community Distributed Generation (CDG), gaining popularity with those who may not own or have access to a viable roof. Urban areas like NYC, which have a large population of renters, are particularly well suited for CS projects where credits from the power produced by a large remote installation are offered on a subscription basis to residents or businesses in the community. However, CS and CS+S projects have stalled at the doorstep of many cities. Host site owners, particularly those with large rooftops, have been slow to commit to installing CS due to competing rooftop usage and programs, limited knowledge about incentives, lack of economic data, and a complicated implementation process.

14 SOLAR ENERGY↗
DOE OSTI2021

Effect of substitutional doping and disorder on the phase stability, magnetism, and half-metallicity of Heusler alloys

Spintronics is the fast growing field that will play a key role in optimizing power consumption, memory, and processing capabilities of nanoelectronic devices. Heusler alloys are potential candidates for application in spintronics due to their room temperature (RT) half-metallicity, high Curie temperature, low lattice mismatch with most substrates, and strong control on electronic density of states at Fermi level. In this work, we investigate the effect of substitutional doping and disorder on the half-metallicity, phase stability, and magnetism of Heusler alloys using density functional theory methods. Our study shows that electronic and magnetic properties of half/full-Heusler alloys can be tuned by changing electron-count through controlled variation of chemical compositions of alloying elements. We provide a detailed discussion on the effect of substitutional doping and disorder on the tunability of half-metallic nature of Co 2 MnX and NiMnX based Heusler alloys, where X represents group 13–16 and period 3–6 elements of the periodic table. Based on the idea of electron count and disorder, we predicted a possible existence of thermodynamically stable half-metallic multicomponent bismuthides, for example, (CuNi 3 )Mn 4 Bi 4 and (ZnNi 7 )Mn 8 Bi 8 , through substitution doping at Ni site by specific Cu and Zn composition in half-Heusler NiMnBi. We believe that the design guide based on electron-counts presented for half-metals will play a key role in electronic-structure engineering of novel Heusler alloys for spintronic application, which will accelerate the development and synthesis of novel materials.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Rapid grain refinement and compositional homogenization in a cast binary Cu50Ni alloy achieved by friction stir processing

Friction stir processing (FSP) has been increasingly adopted for joining and processing materials in automotive, aerospace and industrial construction. During FSP a dynamic competition between high-speed shear deformation and deformation-induced heating brings about a complex competition between multiple dynamic microstructural evolution mechanisms making it difficult to predict the microstructural evolution pathway. Hence, improved understanding of microstructural evolution mechanisms during FSP can be beneficial for continued growth in the adoption of FSP for demanding applications of future. Towards this goal, this study uses a model binary Cu – 50 at.% Ni alloy to clarify the effect of single and double pass FSP on the microstructural evolution of a coarse grained and compositionally heterogeneous cast microstructure. High energy synchrotron X-ray diffraction, electron backscatter diffraction, and nanoindentation are used to clarify the microstructural evolution due to FSP. The process of compositional homogenization of as-cast segregations is studied by energy dispersive spectroscopy and atom probe tomography. Our results show that a single fast FSP pass at 30 mm.s -1 produces a 100 µm deep layer of submicrometric and hall-petch hardened CuNi grains. The initial cast compositional heterogeneities in a micrometric scale is rapidly transformed to nano-sized domains, mainly confined at grain boundaries. Double pass FSP increases the penetration depth of the processed layer and leads to a 2.9 times grain growth relative to single pass FSP. Grain fragmentation, discontinuous dynamic recrystallization, grain growth, and twinning mechanisms are discussed. In conclusion, these results highlight the value of FSP for ultrafast grain refinement and compositional homogenization of cast alloys.

36 MATERIALS SCIENCE↗