Amorphous and Metastable Phase Formation in Systems with Positive Heats of Mixing using High-Rate Sputter Deposition

ABSTRACTThe triode sputtering technique and a “split-target” arrangement were used to produce metastable crystalline and amorphous phases in the Cu-W, Mo-Cu, Ag-Fe, Ag-Cu, Pu-Ta and Pu-V systems. These systems all exhibit liquid and solid immiscibility and have positive heats of mixing and atomic radii that differ by at least 10%. The sputtered coatings, whose thickness varied between 25 and 200 microns, were formed at deposition rates between 35 and 200 Å/s. They were characterized using x-ray diffraction, TEM, microprobe, microhardness, and DSC techniques. The observed amorphous and metastable solid solution phases are discussed in terms of predicated heats of formation for these phases using Miedema's thermodynamic approximations [1] that include chemical, elastic, and structural contributions. Differences in compositional ranges observed by high rate sputter deposition compared to other vapor deposition techniques (e.g., coevaporation) appeared to arise as a result of processes that occur during deposition or immediately following deposition.

Download Full-text

Influence of oxygen impurity on containerless solidification of quasicrystalline-forming Zr80Pt20 alloy

MRS Proceedings ◽

10.1557/opl.2013.426 ◽

2013 ◽

Vol 1528 ◽

Author(s):

Takeshi Harada ◽

Akitoshi Mizuno ◽

Masahito Watanabe

Keyword(s):

Oxygen Content ◽

Doping Level ◽

Metastable Phase ◽

Primary Phase ◽

Oxygen Impurity ◽

X Ray Diffraction ◽

Time Resolved ◽

X Ray ◽

Metastable Phase Formation ◽

Containerless Solidification

ABSTRACTThe influence of oxygen content on containerless solidification of Zr80Pt20 alloy has been studied by using conical nozzle levitation (CNL) technique. The doping level of oxygen from 41 to 5450 ppm mass oxygen (PMO) affects the undercooling of the liquid Zr80Pt20 alloy. Time-resolved synchrotron x-ray diffraction revealed that the quasicrystalline (QC) phase precipitated as a primary phase during solidification of the Zr80Pt20 alloy. The amount of the QC phase depends on the oxygen content in the alloy. This indicates that the doping level of oxygen in Zr80Pt20 alloy can be related to the metastable phase formation as well as the glass-formation ability.

Download Full-text

Stable and Metastable Phase Equilibria Involving the Cu6Sn5 Intermetallic

Journal of Electronic Materials ◽

10.1007/s11664-021-09067-4 ◽

2021 ◽

Author(s):

A. Leineweber ◽

M. Löffler ◽

S. Martin

Keyword(s):

Phase Equilibria ◽

Electron Backscatter Diffraction ◽

Metastable Phase ◽

Stable Phase ◽

X Ray Diffraction ◽

X Ray ◽

Heat Treated ◽

Ordered Phases ◽

Backscatter Diffraction ◽

Kinetics Of

Abstract Cu6Sn5 intermetallic occurs in the form of differently ordered phases η, η′ and η′′. In solder joints, this intermetallic can undergo changes in composition and the state of order without or while interacting with excess Cu and excess Sn in the system, potentially giving rise to detrimental changes in the mechanical properties of the solder. In order to study such processes in fundamental detail and to get more detailed information about the metastable and stable phase equilibria, model alloys consisting of Cu3Sn + Cu6Sn5 as well as Cu6Sn5 + Sn-rich melt were heat treated. Powder x-ray diffraction and scanning electron microscopy supplemented by electron backscatter diffraction were used to investigate the structural and microstructural changes. It was shown that Sn-poor η can increase its Sn content by Cu3Sn precipitation at grain boundaries or by uptake of Sn from the Sn-rich melt. From the kinetics of the former process at 513 K and the grain size of the η phase, we obtained an interdiffusion coefficient in η of (3 ± 1) × 10−16 m2 s−1. Comparison of this value with literature data implies that this value reflects pure volume (inter)diffusion, while Cu6Sn5 growth at low temperature is typically strongly influenced by grain-boundary diffusion. These investigations also confirm that η′′ forming below a composition-dependent transus temperature gradually enriches in Sn content, confirming that Sn-poor η′′ is metastable against decomposition into Cu3Sn and more Sn-rich η or (at lower temperatures) η′. Graphic Abstract

Download Full-text

Structural Formation of UHMWPE Film Tracked by Real-Time Retardation Measurements during Uniaxial/Biaxial Stretching

Materials ◽

10.3390/ma11112292 ◽

2018 ◽

Vol 11 (11) ◽

pp. 2292 ◽

Cited By ~ 2

Author(s):

Yoshinori Hashimoto ◽

Shotaro Nishitsuji ◽

Takashi Kurose ◽

Hiroshi Ito

Keyword(s):

Tensile Testing ◽

X Ray Diffraction ◽

Structural Formation ◽

X Ray ◽

Amorphous Phases ◽

Analysis Techniques ◽

Biaxial Stretching ◽

Thermal Analysis Techniques ◽

Ultra High Molecular Weight ◽

Order Structures

This work reports on an experimental study of the stretching of ultra-high molecular weight polyethylene (UHMWPE) film in various uniaxial/biaxial stretching modes at various temperatures and stretching speeds. We examined the stress-birefringence relationship as a stress-optical rule (SOR) under uniaxial stretching and evaluated the stress-optical coefficient (SOC). Wide-angle X-ray diffraction (WAXD) measurements were applied to evaluate the contribution to birefringence of the crystalline and amorphous phases and to characterize stretching modes. In simultaneous biaxial stretching, the melting temperature (Tm) proved critical to structural formation. We applied thermal analysis techniques and tensile testing to evaluate higher order structures after each stretching mode.

Download Full-text

PHYSICAL PROPERTIES AND MICROSTRUCTURE PERFORMANCE OF LASER ALLOYING Zn MODIFIED AMORPHOUS-NANOCRYSTALS REINFORCED COATING

NANO ◽

10.1142/s1793292013500380 ◽

2013 ◽

Vol 08 (04) ◽

pp. 1350038 ◽

Cited By ~ 2

Author(s):

JIANQUAN LI ◽

HUASHI LIU ◽

JIANING LI ◽

GUOZHONG LI

Keyword(s):

Wear Resistance ◽

Titanium Alloy ◽

Electron Microscope ◽

Crystallization Process ◽

Laser Alloying ◽

X Ray Diffraction ◽

X Ray ◽

Amorphous Phases ◽

Transmission Electron ◽

Improve Wear Resistance

Zn was firstly used to improve wear resistance of a TA7 (Ti–5Al–2.5Sn) titanium alloy surface by mean of a laser alloying (LA) technique. The synthesis of the hard coating on a TA7 titanium alloy by LA of Co–Ti–Cr–TiB2–Zn–CeO2 pre-placed powders was investigated by means of scanning electron microscope (SEM), X-ray diffraction (XRD) and high resolution transmission electron microscope (HRTEM). Experimental results indicated lot of the nanocrystals, such as Ti–B/CoZn13 and the amorphous phases were produced in such LA coating. The nucleation and growth of the amorphous phases were retarded by the nanocrystals in a certain extent during the crystallization process of the amorphous phases. Compared with a TA7 alloy substrate, an improvement of the wear resistance was obtained for such LA composite coating.

Download Full-text

Contribution of the hybrid component to the structure and properties of ceramics based on metastable phases Al2O3

Voprosy Materialovedeniya ◽

10.22349/1994-6716-2021-106-2-127-136 ◽

2021 ◽

pp. 127-136

Author(s):

A. V. Maletsky ◽

T. E. Konstantinova ◽

D. R. Belichko ◽

G. K. Volkova ◽

V. V. Burkhovetsky

Keyword(s):

Mechanical Properties ◽

Yttrium Aluminum Garnet ◽

Metastable Phase ◽

Physical And Mechanical Properties ◽

Structure And Properties ◽

X Ray Diffraction ◽

Mutual Inhibition ◽

X Ray ◽

Tetragonal Lattice ◽

Yttrium Aluminum

The paper presents results of the study of the effect of doping with yttrium oxide on ceramics of the composition (γ + θ) Al2O3 + nY2O3 (n = 0, 1, 2, 3 wt%), sintered at 1550°C for 2 h, from powders of the specified composition annealed at temperatures of 500 , 800, 1000°С. X-ray diffraction analysis established the formation in ceramics of yttrium aluminum garnet Y3Al5O12 (YAG) and a metastable phase of the same composition with a tetragonal lattice type in powders at temperatures above 1200°C. The effect of YAG on the physical and mechanical properties was established: high properties were demonstrated by ceramics of the composition α-Al2O3 + 2wt% Y2O3, obtained from a powder annealed at 1000°C. In addition, high physical and mechanical properties were observed in ceramics of the composition α-Al2O3 + 0wt% Y2O3, obtained from a powder annealed at 800°C. The effect of the so-called “mutual protection against crystallization” was discovered, which consists in the mutual inhibition of crystallization processes in powders of the Al2O3 – Y2O3 system.

Download Full-text

Quantitative Evaluation of Crystalline and Amorphous Phases in Clay-Based Cordierite Ceramic

Minerals ◽

10.3390/min10121122 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1122

Author(s):

Zdeněk Klika ◽

Marta Valášková ◽

Lucie Bartoňová ◽

Petra Maierová

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Chemical Analysis ◽

Test Results ◽

Mineral Analysis ◽

X Ray Diffraction ◽

X Ray ◽

Amorphous Phases ◽

Cordierite Ceramic ◽

Scanning Electron

An innovative chemical quantitative mineral analysis (CQMA) was successfully tested on a cordierite-based clay ceramic sample to quantify crystalline and amorphous components. The accuracy of this method was demonstrated on an added module to the CQMA program that used oxide formulas of amorphous phases obtained by energy dispersive X-ray spectroscopy (EDS) microprobe chemical analysis. This CQMA method was tested for three variants calculated using chemical analysis, i.e., X-ray diffraction (XRD) identification of crystalline (cordierite and enstatite) and amorphous phases by scanning electron microscopy (SEM)/EDS texture and microanalyses. The test results from CQMA suggest their application possibilities as well as the limits of their utilization.

Download Full-text

The Use of BaF2 Buffer Layers for the Sputter-Deposition of Ticabacuo Thin-Film Superconductors

MRS Proceedings ◽

10.1557/proc-169-671 ◽

1989 ◽

Vol 169 ◽

Author(s):

K.M. Hubbard ◽

P.N. Arendt ◽

D.R. Brown ◽

D.W. Cooke ◽

N.E. Elliott ◽

...

Keyword(s):

Thin Film ◽

Thin Films ◽

Sputter Deposition ◽

Buffer Layers ◽

X Ray Diffraction ◽

Dc Magnetron Sputtering ◽

X Ray ◽

Film Substrate ◽

Ion Backscattering ◽

Scanning Electron

AbstractThin films of the Tl‐based superconductors often have relatively poor properties because of film/substrate interdiffusion which occurs during the anneal. We have therefore investigated the use of BaF2 as a diffusion barrier. TICaBaCuO thin films were deposited by dc magnetron sputtering onto MgO <100> substrates, both with and without an evaporation‐deposited BaF2 buffer layer, and post‐annealed in a Tl over‐pressure. Electrical properties of the films were determined by four‐point probe analysis, and compositions were measured by ion‐backscattering spectroscopy. Structural analysis was performed by X‐ray diffraction and scanning electron microscopy. The BaF2 buffer layers were found to significantly improve the properties of the TICaBaCuO thin films.

Download Full-text

Substrates Effect on the Phase Transition of GaN Thin Films by Sputter Deposition

Materials Science Forum ◽

10.4028/www.scientific.net/msf.971.79 ◽

2019 ◽

Vol 971 ◽

pp. 79-84

Author(s):

Chun Guang Zhang

Keyword(s):

Thin Films ◽

Phase Transition ◽

Nitrogen Atmosphere ◽

Sputter Deposition ◽

X Ray Diffraction ◽

Pure Nitrogen ◽

X Ray ◽

Zinc Blende ◽

Planar Magnetron ◽

Pure Nitrogen Atmosphere

As a promising third generation semiconductor material, gallium nitride (GaN) has become a research hotspot in optoelectronic field nowadays. In this paper, GaN thin films were grown by radio frequency (RF) planar magnetron sputtering of a powder GaN target in a pure nitrogen atmosphere at (0.2 – 2.0) Pa, (10 - 100) W onto various substrates such as GaAs (100), Si (100), Si (111), Al2O3(0001) and glass without any buffer layer. A clear phase transition from the metastable cubic zinc-blende (c - ZB) to the stable hexagonal wurtzite (h - WZ) dependence on substrates has been found in the GaN thin films. And the phase transition of GaN films were studied by X-ray diffraction (XRD), photoluminescence (PL) and Raman spectroscopy.

Download Full-text

Deformation-Induced Amorphization of Crystalline Particles in a Cu-Ti Metallic Glass

MRS Proceedings ◽

10.1557/proc-80-83 ◽

1986 ◽

Vol 80 ◽

Cited By ~ 1

Author(s):

Eduardo A. Kamenetzky ◽

Philip D. Asikenazy ◽

Lee E. Tanner ◽

William L. Johnson

Keyword(s):

Amorphous Matrix ◽

Structural Evolution ◽

Convergent Beam Electron Diffraction ◽

Transformation Process ◽

Morphological Description ◽

X Ray Diffraction ◽

Initial Particle ◽

X Ray ◽

Amorphous Phases ◽

Convergent Beam

AbstractCrystalline particles and grains embedded in Cu35Ti65 glass ribbons have been amorphized by isothermal cold rolling. The structural evolution has been studied by X-ray diffraction and TEM techniques. Initial particle morphologies are spherulitic and spherical, the latter with sizes ranging between 10 and 100 nm. The new amorphous phase seems to nucleate at crystalline-amorphous matrix interfaces. Initially there is a well defined interface between the new and the existing amorphous phases but it disappears as rolling progresses. Crystallites on a nanoscale still present in the final stages of particle amorphization have been observed by convergent beam electron diffraction. After sufficient deformation the consolidated ribbon becomes completely glassy. A morphological description of the transformation process in terms of crystal destabilization and solid-state particle melting is presented.

Download Full-text