Angel Aleman

University of California, Los Angeles

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Suneel Kodambaka

Virginia Tech

Hicham Zaid

University of California, Los Angeles

Kōichi Tanaka

Niigata University of Health and Welfare

Mark S. Goorsky

University of California, Los Angeles

Hanna Kindlund

Virginia Tech

Michael E. Liao

University of California, Los Angeles

J.‐M. Yang

Qingdao Agricultural University

Joshua Fankhauser

University of California, Los Angeles

Chao Li

Southern University of Science and Technology

Koki Hojo

Nagoya University

Cooperative Institutions

University of California, Los Angeles

California NanoSystems Institute

Nagoya University

United States Naval Research Laboratory

University of Illinois Urbana-Champaign

Materials Science & Engineering

Colorado School of Mines

University of California System

Los Angeles City College

Northeastern University

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Ultra-high vacuum dc magnetron sputter-deposition of 0001-textured trigonal α-Ta2C/Al2O3(0001) thin films

Materialia (2020)

Kōichi Tanaka Angel Aleman Hicham Zaid Michael E. Liao Koki Hojo

Texture (cosmology)

Cavity magnetron

Deposition

10.1016/j.mtla.2020.100838

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Citations (7)

Influence of ultra-low ethylene partial pressure on microstructural and compositional evolution of sputter-deposited Zr-C thin films

Surface and Coatings Technology (2020)

Hicham Zaid Angel Aleman Kōichi Tanaka Chao Li Pascal Berger

Torr

Partial pressure

10.1016/j.surfcoat.2020.126053

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Citations (7)

Kinetics of Zr-Al intermetallic compound formation during ultra-high vacuum magnetron sputter-deposition of Zr/Al2O3(0001) thin films

Acta Materialia (2018)

Kōichi Tanaka Joshua Fankhauser Hicham Zaid Angel Aleman Masaki Sato

Orthorhombic crystal system

10.1016/j.actamat.2018.04.018

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Citations (12)

Ultrahigh vacuum dc magnetron sputter-deposition of epitaxial Pd(111)/Al2O3(0001) thin films

Journal of Vacuum Science & Technology A Vacuum Surfaces and Films (2018)

Angel Aleman Chao Li Hicham Zaid Hanna Kindlund Joshua Fankhauser

Pd(111) thin films, ∼245 nm thick, are deposited on Al2O3(0001) substrates at ≈0.5Tm, where Tm is the Pd melting point, by ultrahigh vacuum dc magnetron sputtering of Pd target in pure Ar discharges. Auger electron spectra and low-energy electron diffraction patterns acquired in situ from the as-deposited samples reveal that the surfaces are compositionally pure 111-oriented Pd. Double-axis x-ray diffraction (XRD) ω-2θ scans show only the set of Pd 111 peaks from the film. In triple-axis high-resolution XRD, the full width at half maximum intensity Γω of the Pd 111 ω-rocking curve is 630 arc sec. XRD 111 pole figure obtained from the sample revealed six peaks 60°-apart at a tilt angles corresponding to Pd 111 reflections. XRD ϕ scans show six 60°-rotated 111 peaks of Pd at the same ϕ angles for 11[Formula: see text]3 of Al2O3 based on which the epitaxial crystallographic relationships between the film and the substrate are determined as [Formula: see text]ǁ[Formula: see text] with two in-plane orientations of [Formula: see text]ǁ[Formula: see text] and [Formula: see text]ǁ[Formula: see text]. Using triple axis symmetric and asymmetric reciprocal space maps, interplanar spacings of out-of-plane (111) and in-plane (11[Formula: see text]) are found to be 0.2242 ± 0.0003 and 0.1591 ± 0.0003 nm, respectively. These values are 0.18% lower than 0.2246 nm for (111) and the same, within the measurement uncertainties, as 0.1588 nm for (11[Formula: see text]) calculated from the bulk Pd lattice parameter, suggesting a small out-of-plane compressive strain and an in-plane tensile strain related to the thermal strain upon cooling the sample from the deposition temperature to room temperature. High-resolution cross-sectional transmission electron microscopy coupled with energy dispersive x-ray spectra obtained from the Pd(111)/Al2O3(0001) samples indicate that the Pd-Al2O3 interfaces are essentially atomically abrupt and dislocation-free. These results demonstrate the growth of epitaxial Pd thin films with (111) out-of-plane orientation with low mosaicity on Al2O3(0001).

Auger electron spectroscopy

Pole figure

Low-energy electron diffraction

10.1116/1.5021609

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Citations (20)

Size-dependent yielding and strain-hardening of compositionally-enriched body-centered cubic VNbTaMoW alloy

Scripta Materialia (2020)

Hicham Zaid Angel Aleman Suneel Kodambaka

Strain hardening exponent

Hardening (computing)

Cubic crystal system

Grain boundary strengthening

10.1016/j.scriptamat.2019.12.028

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Citations (11)

Unusual Secondary Slip Activity at Room Temperature in VC Single Crystals

Angel Aleman Hicham Zaid Kōichi Tanaka J.‐M. Yang Suneel Kodambaka

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10.2139/ssrn.4797802

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Room-temperature plasticity and size-dependent mechanical responses in small-scale B1-NbC(001) single-crystals

Acta Materialia (2021)

Angel Aleman Hicham Zaid Brandon Cruz Kōichi Tanaka J.‐M. Yang

Indentation

Hardening (computing)

Strain hardening exponent

10.1016/j.actamat.2021.117384

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Citations (8)

Room-Temperature Plasticity and Size-Dependent Mechanical Responses in Small-Scale B1-NbC(001) Single-Crystals

SSRN Electronic Journal (2021)

Angel Aleman Hicham Zaid Brandon Cruz Kōichi Tanaka J.‐M. Yang

We report on the mechanical responses of NbC(001) single-crystals subjected to nanoindentation and in situ scanning electron microscopy based uniaxial microcompression tests at room-temperature. Using X-ray diffraction and X-ray photoelectron spectroscopy, we determine that the as-purchased bulk NbC is a 001-oriented B1-structured single-crystal with lattice parameter of 0.4446 ± 0.0002 nm and C/Nb ratio of ~0.99. From nanoindentation experiments performed on the bulk crystal using a Berkovich diamond indenter, we measure an elastic modulus of 495 ± 14 GPa and an indentation-depth (h) dependent hardness decreasing from 31.0 ± 1.2 GPa at h = 0.2 µm to 26.4 ± 0.4 GPa at h = 0.9 µm. During uniaxial compression of cylindrical pillars with top diameters D between ~0.25 µm and ~0.75 µm, we observe strain hardening, increasing yield strengths with decreasing D, and surprisingly extensive plastic deformation with strains exceeding 2% and up to 30% in larger-size pillars. Electron microscopy characterization of the compressed pillars reveal slip traces characteristic of {110}〈1‾10〉 and {111}〈1‾10〉 slip systems. We suggest that the unexpected activation of {111}〈1‾10〉 facilitates plasticity in NbC(001).

10.2139/ssrn.3906847

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Growth of heterolayered [cubic-TaC(111) + rhombohedral-Ta3C2(0001)] nanocomposite thin films on Al2O3(0001)

Acta Materialia (2020)

Kōichi Tanaka Michael E. Liao Angel Aleman Hicham Zaid Mark S. Goorsky

Stoichiometry

10.1016/j.actamat.2020.116499

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Citations (4)

Unusual secondary slip activity at room temperature in VC single crystals

Materials & Design (2024)

Angel Aleman Hicham Zaid Kōichi Tanaka Jenn‐Ming Yang Suneel Kodambaka

Cubic transition-metal carbides are high-melting compounds with remarkable high-temperature mechanical properties but are generally considered to be brittle at low-temperatures. Here, we report on the activation of multiple slip systems and plasticity in 001, 110, and 111 oriented vanadium carbide (VC) single-crystals subjected to uniaxial compression at room-temperature. Using in situ scanning electron microscopy based mechanical testing, we observe plastic strains up to 21%, size-dependent yielding, and work hardening in VC(0 0 1) and VC(1 1 1). In comparison, VC(1 1 0) crystals are relatively brittle with limited localized plasticity. VC(1 1 1) crystals exhibit the highest yield strengths of up to ∼23 GPa while VC(0 0 1) crystals are some of the softest with yield strengths as low as ∼13 GPa. For loading along [1 1 0], we find that only the primary slip system, {1 1 1}〈11¯0〉, is active. In VC(0 0 1) and VC(1 1 1), we find the operation of two sets of slip systems, [{1 1 0}〈11¯0〉 and {1 1 1}〈11¯0〉] and [{1 1 1}〈11¯0〉 and {1 0 0}〈11¯0〉], respectively. Intriguingly, the estimated critical resolved shear stresses for all the three slip systems are nearly the same. Our results, which reveal orientation-dependent differences in the activity of the same slip system, provide new insights into plastic deformation in refractory compounds.

Brittleness

Hardening (computing)

10.1016/j.matdes.2024.113195

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