The structural features of the amorphous C14 HfNiAl Laves phase

2018 ◽  
Vol 2 (89) ◽  
pp. 49-54
Author(s):  
S.I. Mudry ◽  
O.V. Shved ◽  
Yu.O. Kulyk ◽  
I.I. Bulyk ◽  
A.K. Borysiuk
Keyword(s):  
High Temperature ◽  
Xrd Analysis ◽  
Structural Features ◽  
Hydrogen Atmosphere ◽  
Al Alloys ◽  
Laves Phase ◽  
Hydrogen Treatment ◽  
Glass Forming ◽  
Controlled Structure ◽  
High Possibility

Purpose: In order to clarify whether amorphization occurs in the pseudo-binary C14 HfNi0.6Al1.4 Laves phase a detailed investigation of the effect of hydrogen treatment on it phase-structural state has been studied. This type of compounds is of interest due to their high possibility to hydrogen absorption as Laves phase structures and as Hf-Ni alloys. Design/methodology/approach: We used a combination of hydrogen treatment and grinding methods for studying of the processes of controlled structure formation. High temperature transformations of the HfNi0.6Al1.4 alloy were pointed out by means of XRD analysis. Findings: By combination of two amorphization methods and high temperature measurements we have observed a phase structural transformation of the HfNi0.6Al1.4 alloy, which could be presented as: HfNi0.6Al1.4(cryst.) + H2 ® HfNi0.6Al1.4 (nanocryst.) + HfNi0.6Al1.4 (amorphous) + H2 ® HfH2 (amorphous) + AlH3 (amorphous) + Ni. Ferromagnetic- like properties of the pseudo-binary HfNi0.6Al1.4 Laves phase was found. Research limitations/implications: Complex research of HfNi0.6Al1.4 alloy revealed various structure features depending on phase content, thermodynamic parameters and conditions of hydrogen treatment. Obtained results suppose that further studies of structure and physical properties of Hf-Ni-Al alloys will allow to find the methods to control the producing of materials with desired properties. Practical implications: Using of hydrogen treatment is effective to produce Al-based alloys with improved magnetic properties. Originality/value: Treatment in hydrogen atmosphere allows improving the glass-forming ability in Hf-Ni-Al alloys.

Electron Microscopy of Silicon Nitride-Based Ceramics

1991 ◽  
Vol 49 ◽  
pp. 926-927
Author(s):  
Gareth Thomas
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Silicon Nitride ◽  
World Wide ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
High Temperature Strength ◽  
Sintering Additives ◽  
Glass Forming ◽  
Dense Product

Silicon nitride and silicon nitride based-ceramics are now well known for their potential as hightemperature structural materials, e.g. in engines. However, as is the case for many ceramics, in order to produce a dense product, sintering additives are utilized which allow liquid-phase sintering to occur; but upon cooling from the sintering temperature residual intergranular phases are formed which can be deleterious to high-temperature strength and oxidation resistance, especially if these phases are nonviscous glasses. Many oxide sintering additives have been utilized in processing attempts world-wide to produce dense creep resistant components using Si3N4 but the problem of controlling intergranular phases requires an understanding of the glass forming and subsequent glass-crystalline transformations that can occur at the grain boundaries.

Low-Temperature Post-Oxidation Annealing Using Atomic Hydrogen Radicals Generated by High-Temperature Catalyzer for Improvement in Reliability of Thermal Oxides on 4H-SiC

2006 ◽  
Vol 527-529 ◽  
pp. 999-1002
Author(s):  
Junji Senzaki ◽  
Atsushi Shimozato ◽  
Kenji Fukuda
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Atomic Hydrogen ◽  
High Reliability ◽  
Hydrogen Atmosphere ◽  
Exposed Sample ◽  
New Apparatus ◽  
Hydrogen Radical ◽  
Hydrogen Radicals ◽  
Sic Wafer

Low-temperature post-oxidation annealing (POA) process of high-reliability thermal oxides grown on 4H-SiC using new apparatus that generates atomic hydrogen radicals by high-temperature catalyzer has been investigated. Atomic hydrogen radicals were generated by thermal decomposition of H2 gas at the catalyzer surface heated at high temperature of 1800°C, and then exposed to the sample at 500°C in reactor pressure of 20 Pa. The mode and maximum values of field-to-breakdown are 11.0 and 11.2 MV/cm, respectively, for the atomic hydrogen radical exposed sample. In addition, the charge-to-breakdown at 63% cumulative failure of the thermal oxides for atomic hydrogen radical exposed sample was 0.51 C/cm2, which was higher than that annealed at 800°C in hydrogen atmosphere (0.39 C/cm2). Consequently, the atomic hydrogen radical exposure at 500°C has remarkably improved the reliability of thermal oxides on 4H-SiC wafer, and is the same effect with high-temperature hydrogen POA at 800°C.

Structural topological signature of high-temperature non-Arrhenius crossover in metallic glass-forming liquids

2021 ◽  
Vol 200 ◽  
pp. 113926
Author(s):  
Nannan Ren ◽  
Lina Hu ◽  
Bing Wang ◽  
Kaikai Song ◽  
Pengfei Guan
Keyword(s):  
High Temperature ◽  
Metallic Glass ◽  
Glass Forming

Structural features and enhanced high-temperature oxygen ion transport in SrFe1−xTaxO3−δ

2013 ◽  
Vol 197 ◽  
pp. 191-197 ◽  
Author(s):  
Alexey A. Markov ◽  
Elizaveta V. Shalaeva ◽  
Alexander P. Tyutyunnik ◽  
Vasily V. Kuchin ◽  
Mikhail V. Patrakeev ◽  
...  
Keyword(s):  
High Temperature ◽  
Ion Transport ◽  
Structural Features ◽  
Oxygen Ion

scholarly journals In-Situ X-ray Diffraction Measurement for Pure Niobium Metal in High Temperature Hydrogen Atmosphere

2006 ◽  
Vol 70 (6) ◽  
pp. 467-472 ◽  
Author(s):  
Tomonori Nambu ◽  
Nobue Shimizu ◽  
Hisakazu Ezaki ◽  
Hiroshi Yukawa ◽  
Masahiko Morinaga ◽  
...  
Keyword(s):  
High Temperature ◽  
Hydrogen Atmosphere ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pure Niobium

scholarly journals Simultaneous Measurement of Temperature and Refractive Index Using High Temperature Resistant Pure Quartz Grating Based on Femtosecond Laser and HF Etching

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1028
Author(s):  
Na Zhao ◽  
Qijing Lin ◽  
Kun Yao ◽  
Fuzheng Zhang ◽  
Bian Tian ◽  
...  
Keyword(s):  
Refractive Index ◽  
High Temperature ◽  
Femtosecond Laser ◽  
Optical Fiber ◽  
Temperature Response ◽  
High Sensitivity ◽  
Xrd Analysis ◽  
Refractive Index Sensor ◽  
Compact Structure ◽  
Fluid Analysis

The optical fiber temperature and refractive index sensor combined with the hollow needle structure for medical treatment can promote the standardization of traditional acupuncture techniques and improve the accuracy of body fluid analysis. A double-parameter sensor based on fiber Bragg grating (FBG) is developed in this paper. The sensor materials are selected through X-ray diffraction (XRD) analysis, and the sensor sensing principle is theoretically analyzed and simulated. Through femtosecond laser writing pure silica fiber, a high temperature resistant wavelength type FBG temperature sensor is obtained, and the FBG is corroded by hydrofluoric acid (HF) to realize a high-sensitivity intensity-type refractive index sensor. Because the light has dual characteristics of energy and wavelength, the sensor can realize simultaneous dual-parameter sensing. The light from the lead-in optical fiber is transmitted to the sensor and affected by temperature and refractive-index; then, the reflection peak is reflected back to the lead-out fiber by the FBG. The high temperature response and the refractive index response of the sensor were measured in the laboratory, and the high temperature characteristics of the sensor were verified in the accredited institute. It is demonstrated that the proposed sensor can achieve temperature sensing up to 1150 °C with the sensitivity of 0.0134 nm/°C, and refractive sensing over a refractive range of 1.333 to 1.4027 with the sensitivity of −49.044 dBm/RIU. The sensor features the advantages of two-parameter measurement, compact structure, and wide temperature range, and it exhibits great potential in acupuncture treatment.

Structural deformation-metamorphism and exhumation processes of Yuanmou metamorphic complex, Yunnan, China

2021 ◽  
Author(s):  
Xuemei Cheng ◽  
Shuyun Cao
Keyword(s):  
High Temperature ◽  
Electron Backscatter Diffraction ◽  
Early Stage ◽  
Structural Features ◽  
Detachment Fault ◽  
Ductile Deformation ◽  
Structural Deformation ◽  
Subsequent Stage ◽  
Metamorphic Complex ◽  
South Central

<p>Within orogenic zone and continental extensional area, it often developed metamorphic complex or metamorphic gneiss dome that widely exposed continental mid-lower crustal rocks, which is an ideal place to study exhumation processes of deep-seated metamorphic complex and rheology. The Yuanmou metamorphic complex is located in the south-central part of the "Kangdian Axis" in the western margin of Qiangtang Block and Yangtze Block, which is a part of the anticline of the Sichuan-Yunnan platform. Many research works mainly focus on the discussion of intrusion ages, aeromagnetic anomalies, and polymetallic deposits. However, the exhumation process and mechanism of the Yuanmou metamorphic complex are rarely discussed and still unclear. This study, based on detailed field geological observations, optical microscopy (OM), cathodoluminescence (CL), electron backscatter diffraction (EBSD) and electron probe (EMPA) were performed to illustrate the geological structure features, deformation-metamorphic evolution process and its tectonic significance of Yuanmou metamorphic complex during the exhumation process. All these analysis results indicate that the Yuanmou metamorphic complex generally exhibits a dome structure with deep metamorphic rocks and deformed rocks of varying degrees widely developed. Mylonitic gneiss and granitic intrusions are located in the footwall of the Yuanmou, which have suffered high-temperature shearing. The mylonitic fabrics and mineral stretching lineations in the deformed rock are strongly developed, forming typical S-L or L-shaped structural features. The high-temperature ductile deformation-metamorphism environment is high amphibolite facies, that is, the temperature range is between 620 ~ 690 ℃ and the pressure is between 0.8 ~ 0.95 Gpa. In the deformed rocks closed to the detachment fault, some of the mylonite fabric features are retained, but most of them have experienced a strongly overprinted retrogression metamorphism and deformation. At the top of the detachment fault zone, it is mainly composed of cataclasites and fault gouge. The comprehensive macro- and microstructural characteristics, geometry, kinematics, and mineral (amphibole, quartz and calcite) EBSD textures indicate that the Yuanmou metamorphic complex has undergone a progressive exhumation process during regional extension, obvious high-temperature plastic deformation-metamorphism in the early stage, and superimposed of low-temperature plastic-brittle and brittle deformation in the subsequent stage, which is also accompanied by strong fluid activities during the exhumation process.</p>

High temperature thermal and mechanical stability of high-strength nanotwinned Al alloys

2019 ◽  
Vol 165 ◽  
pp. 142-152 ◽  
Author(s):  
Qiang Li ◽  
Jaehun Cho ◽  
Sichuang Xue ◽  
Xing Sun ◽  
Yifan Zhang ◽  
...  
Keyword(s):  
High Temperature ◽  
Mechanical Stability ◽  
High Strength ◽  
Al Alloys

scholarly journals Temperature Dependence of Mechanical, Electrical Properties and Crystal Structure of Polyethylene Blends for Cable Insulation

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1922 ◽  
Author(s):  
Lunzhi Li ◽  
Lisheng Zhong ◽  
Kai Zhang ◽  
Jinghui Gao ◽  
Man Xu
Keyword(s):  
High Temperature ◽  
Electrical Properties ◽  
Temperature Dependence ◽  
Elevated Temperatures ◽  
Breakdown Strength ◽  
Temperature Stability ◽  
Xrd Analysis ◽  
Insulation Material ◽  
Cable Insulation ◽  
Polyethylene Blends

There is a long-standing puzzle concerning whether polyethylene blends are a suitable substitution for cable-insulation-used crosslinking polyethylene (XLPE) especially at elevated temperatures. In this paper, we investigate temperature dependence of mechanical, electrical properties of blends with 70 wt % linear low density polyethylene (LLDPE) and 30 wt % high density polyethylene (HDPE) (abbreviated as 70 L-30 H). Our results show that the dielectric loss of 70 L-30 H is about an order of magnitude lower than XLPE, and the AC breakdown strength is 22% higher than XLPE at 90 °C. Moreover, the dynamic mechanical thermal analysis (DMA) measurement and hot set tests suggest that the blends shows optimal mechanical properties especially at high temperature with considerable temperature stability. Further scanning electron microscope (SEM) observation and X-ray diffraction (XRD) analysis uncover the reason for the excellent high temperature performance and temperature stability, which can be ascribed to the uniform fine-spherulite structure in 70 L-30 H blends with high crystallinity sustaining at high temperature. Therefore, our findings may enable the potential application of the blends as cable insulation material with higher thermal-endurance ability.

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