scholarly journals Amorphization and nanocrystal formation in a Pd–Ni–Cu–P alloy after cooling under different conditions

2022 ◽  
Vol 380 (2217) ◽  
Author(s):  
E. V. Kharanzhevskiy ◽  
P. K. Galenko ◽  
M. Rettenmayr ◽  
S. Koch ◽  
R. Wonneberger ◽  
...  
Keyword(s):  
Electron Probe ◽  
Amorphous Matrix ◽  
Composition Studies ◽  
Diffraction Method ◽  
X Ray Diffraction ◽  
Theme Issue ◽  
Scanning Calorimetry ◽  
Transmission Microscopy ◽  
X Ray ◽  
Nanocrystal Formation

Structure formation during solidification of a Pd–Ni–Cu–P melt is studied. It is demonstrated that changes in the heat transfer conditions lead to a nonlinear change in the characteristics of the structure. The article presents the regimes of cooling the samples and the results of their structure and composition studies. It is found that a decrease in the cooling rate of the alloy leads to an increase in the size, proportion and composition of nanoinclusions in an amorphous matrix. X-ray diffraction method, electron probe microanalysis, transmission microscopy and scanning calorimetry are used for samples characterization. This article is part of the theme issue ‘Transport phenomena in complex systems (part 2)’.

Structures and phase transitions in a new ferroelectric – pyridinium chlorochromate – studied by X-ray diffraction, DSC and dielectric methods

2012 ◽  
Vol 68 (2) ◽  
pp. 128-136 ◽  
Author(s):  
Hanna Małuszyńska ◽  
Piotr Czarnecki ◽  
Anna Czarnecka ◽  
Zdzisław Pająk
Keyword(s):  
Phase Transitions ◽  
Pyridinium Salt ◽  
Diffraction Method ◽  
Phase Iii ◽  
Pyridinium Chlorochromate ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Intermediate Phases ◽  
Ferroelectric Hysteresis

Pyridinium chlorochromate, [C5H5NH]+[ClCrO3]− (hereafter referred to as PyClCrO3), was studied by X-ray diffraction, differential scanning calorimetry (DSC) and dielectric methods. Studies reveal three reversible phase transitions at 346, 316 and 170 K with the following phase sequence: R\bar 3m (I) → R3m (II) → Cm (III) → Cc (IV), c′ = 2c. PyClCrO3 is the first pyridinium salt in which all four phases have been successfully characterized by a single-crystal X-ray diffraction method. Structural results together with dielectric and calorimetric studies allow the classification of the two intermediate phases (II) and (III) as ferroelectric with the Curie point at 346 K, and the lowest phase (IV) as most probably ferroelectric. The ferroelectric hysteresis loop was observed only in phase (III). The high ionic conductivity hindered its observation in phase (II).

X-ray diffraction studies of rapid cooled Al-V and Al-Fe-V alloys

2019 ◽  
Vol 1 (96 extended issue) ◽  
pp. 5-11
Author(s):  
O. Shved ◽  
S. Mudry ◽  
V. Girzhon ◽  
O. Smolyakov
Keyword(s):  
Mechanical Properties ◽  
Physical Properties ◽  
Amorphous Matrix ◽  
Diffraction Method ◽  
Ternary Alloys ◽  
X Ray Diffraction ◽  
Rapid Cooling ◽  
X Ray ◽  
Cell Parameters ◽  
Nonequilibrium Conditions

Purpose: of this paper is to deep and more complete knowledge about the features of phase and structure formation in Al-based alloys with transition metals (TM) Fe and V at rapid cooling from melt. It is known, that nonequilibrium synthesis conditions of such alloys lead to quasicrystalline, amorphous or metastable phases formation, which can significantly improve the physical-chemical properties and first of all the mechanical ones. But understanding of compositional dependences of structure features at formation under nonequilibrium conditions and the correlation of these dependences with physical properties of alloys is far to be clear. Design/methodology/approach: Structure of Al-enriched Al-V, Al-V-Fe rapid cooled alloys was studied by X-ray diffraction method. In order to estimate the influence of structural state of alloy on the mechanical properties the integral microhardness was studied by Vickers method. Findings: Two quasicrystalline icosaedral phases with different cell parameters are revealed in ternary alloys Al100-3xV2xFex (x=2-4). Increasing of transition metal content promotes the formation of phase with higher quasicell parameter embedded in amorphous matrix. With increasing of the transition elements total content from 6 up to 12 at. % the microhardness of alloys increased gradually from 867 to 3050 MPa. Research limitations/implications: Research of nonequilibrium alloys revealed crystalline structure of Al-V alloys and quasicrystalline embedded in amorphous matrix of Al-Fe-V ternary alloys. Obtained results suppose that further structure and physical properties studies of Al-Fe-V alloys will allows to find the conditions to control the producing of materials with desired properties. Practical implications: Using of rapid cooling method for synthesis of Al-enriched Al-Fe-V alloys give an opportunity to produce alloys with significantly improved mechanical properties. Originality/value: Nonequilibrium conditions of cooling allow significantly changes the structure and properties.

Phase equilibria and crystal chemistry in the Y2O3–Al2O3–SiO2 system

1999 ◽  
Vol 14 (2) ◽  
pp. 447-455 ◽  
Author(s):  
U. Kolitsch ◽  
H. J. Seifert ◽  
T. Ludwig ◽  
F. Aldinger
Keyword(s):  
Phase Equilibria ◽  
Electron Probe ◽  
Eutectic Temperature ◽  
Ternary Eutectic ◽  
Ternary Solid Solution ◽  
Temperature Differential ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Electron Probe Microanalyzer

In order to clarify inconsistencies in the literature and to verify assumed ternary solubilities, the phase equilibria in the Y2O3–Al2O3 –SiO2 system at 1600, 1400, and 1300 °C were experimentally determined using x-ray diffraction (XRD), scanning electron microscope with attached energy-dispersive detector system (SEM-EDX), and electron probe microanalyzer (EPMA). Six quasibinary phases were observed: Y4Al2O9 (YAM), YAlO3 (YAP), Y3Al5O12 (YAG), Y2SiO5, Y2Si2O7 (C and D modifications), and ˜3Al2O3· 2SiO2 (mullite). Y4Al2O9 forms an extended ternary solid solution with the formula Y4Al2(1-x)Si2xO9+x (x = 0 2 ˜0.31). The lowest ternary eutectic temperature was determined at 1371 ± 5 °C by high-temperature differential scanning calorimetry (DSC). The results were compared with previous data available for the Y2O3–Al2O3 –SiO2 system and with data for other RE2O3–Al2O3 –SiO2 (RE = rare earth element) systems.

Nanocrystalline ZrN particles embedded in Zr-Fe-Cu-Al-Ni amorphous matrix.

2002 ◽  
Vol 754 ◽  
Author(s):  
Marisa A. Bab ◽  
Laura C. Damonte ◽  
Luis Mendoza-Zélis ◽  
Stefano Deledda ◽  
Jurgen Eckert
Keyword(s):  
Amorphous Matrix ◽  
Nitrogen Atmosphere ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Late Transition Metals ◽  
Amorphous Ribbons ◽  
Melt Spun ◽  
Late Transition ◽  
Thermal Stability Of

ABSTRACTMelt-spun Zr64Al7Cu17Ni10Fe2 amorphous ribbons were milled under nitrogen atmosphere for different times. The resulting nitrided powders were studied by x-ray diffraction, Mössbauer spectroscopy and differential scanning calorimetry. The formation of nanosized crystalline particles, with cubic δ-ZrN structure, dispersed in the amorphous matrix was observed along with a change in the composition of the amorphous phase. Prolonged milling leads to the additional precipitation of late transition metals (Fe,Ni,Cu). The nitride particles affect the crystallization behavior and modify the thermal stability of the amorphous alloy.

Pressure-induced nanocrystallization of Zr55Al10Ni5Cu30 bulk metallic glass

2002 ◽  
Vol 17 (11) ◽  
pp. 2935-2939 ◽  
Author(s):  
Jia Zhang ◽  
K. Q. Qiu ◽  
A. M. Wang ◽  
H. F. Zhang ◽  
M. X. Quan ◽  
...  
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Amorphous Matrix ◽  
Ambient Pressure ◽  
Applied Pressure ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Crystallization Fraction

The effect of pressure on the crystallization behavior of Zr55Al10Ni5Cu30 bulk metallic glass was investigated by differential scanning calorimetry, x-ray diffraction, and transmission electron microscopy. Although the crystallization products under high pressure were about the same as those under ambient pressure, the evident changes in the relative crystallization fraction of each phase were observed. The applied pressure enhanced the crystallization temperature. Pressure annealing of the bulk metallic glass produced a composite with dispersion of very fine nanocrystallites in the amorphous matrix. A full nanocrystallization was obtained for the sample annealed under 5 GPa at 793 K. The mechanism for the pressure-induced nanocrystallization is discussed.

scholarly journals Effect of Transition Elements on the Thermal Stability of Glassy Alloys 82Al–16Fe–2TM (TM: Ti, Ni, Cu) Prepared by Mechanical Alloying

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3978
Author(s):  
Nguyen Thi Hoang Oanh ◽  
Do Nam Binh ◽  
Dung Dang Duc ◽  
Quyen Hoang Thi Ngoc ◽  
Nguyen Hoang Viet
Keyword(s):  
Thermal Stability ◽  
Crystallization Process ◽  
Amorphous Matrix ◽  
Intermetallic Phases ◽  
Transition Elements ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Glassy Alloys ◽  
Thermal Stability Of

In the present study, the thermal stability and crystallization behavior of mechanical alloyed metallic glassy Al82Fe16Ti2, Al82Fe16Ni2, and Al82Fe16Cu2 were investigated. The microstructure of the milled powders was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The results showed remarkable distinction in thermal stability of the alloys by varying only two atomic percentages of transition elements. Among them, Al82Fe16Ti2 alloy shows the highest thermal stability compared to the others. In the crystallization process, exothermal peaks corresponding to precipitation of fcc-Al and intermetallic phases from amorphous matrix were observed.

Impact of Rutile Fraction on TiO2 Visible-Light Absorption and Visible-Light-Induced Photocatalytic Activity

2018 ◽  
Author(s):  
David Maria Tobaldi ◽  
Luc Lajaunie ◽  
ana caetano ◽  
nejc rozman ◽  
Maria Paula Seabra ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Light Absorption ◽  
Solid Phase ◽  
Diffraction Method ◽  
Band Alignment ◽  
Quantitative Phase Analysis ◽  
Transmission Microscopy ◽  
Visible Light Absorption ◽  
X Ray

<div>Titanium dioxide is by far the most utilised semiconductor material for photocatalytic applications. Still, it is transparent to visible-light. Recently, it has been proved that a type-II band alignment for the rutile−anatase mixture would improve its visible-light absorption.</div><div>In this research paper we thoroughly characterised the real crystalline and amorphous phases of synthesised titanias – thermally treated at different temperatures to get distinct ratios of anatase-rutile-amorphous fraction – as well as that of three commercially available photocatalytic nano-TiO2. </div><div>The structural characterisation was done via advanced X-ray diffraction method, namely the Rietveld-RIR method, to attain a full quantitative phase analysis of the specimens. The microstructure was also investigated via an advanced X-ray method, the whole powder pattern modelling. These methods were validated combining advanced aberration-corrected scanning transmission microscopy and high-resolution electron energy-loss spectroscopy. The photocatalytic activity was assessed in the liquid- and gas-solid phase (employing rhodamine B and 4-chlorophenol, and isopropanol, respectively, as the organic substances to degrade) using a light source irradiating exclusively in the visible-range.</div><div>Optical spectroscopy showed that even a small fraction of rutile (2 wt%) is able to shift to lower energies the apparent optical band gap of an anatase-rutile mixed phase. But is this enough to attain a real photocatalytic activity promoted by merely visible-light?</div><div>We tried to give a reply to that question.</div><div>Photocatalytic activity results in the liquid-solid phase showed that a high surface hydroxylation led to specimen with superior visible light-induced catalytic activity (i.e. dye and ligand-to-metal charge transfer complexes sensitisation effects). That is: not photocatalysis <i>sensu-strictu</i>.</div><div>On the other hand, the gas-solid phase results showed that a higher amount of the rutile fraction (around 10 wt%), together with less recombination of the charge carriers, were more effective for an actual photocatalytic oxidation of isopropanol.</div>

Studies on the Preparation, Characterization and Solubility of -Cyclodextrin-Roxythromycin Inclusion Complexes

2009 ◽  
Vol 2 (2) ◽  
pp. 523-530
Author(s):  
D. Nagasamy Venkatesh ◽  
S. Karthick ◽  
M. Umesh ◽  
G. Vivek ◽  
R.M. Valliappan ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Inclusion Complexes ◽  
Phase Solubility ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Ir Studies ◽  
Poorly Soluble ◽  
Poorly Soluble Drug

Roxythromycin/ β-cyclodextrin (Roxy/ β-CD) dispersions were prepared with a view to study the influence of β-CD on the solubility and dissolution rate of this poorly soluble drug. Phase-solubility profile indicated that the solubility of roxythromycin was significantly increased in the presence of β-cyclodextrin and was classified as AL-type, indicating the 1:1 stoichiometric inclusion complexes. Physical characterization of the prepared systems was carried out by differential scanning calorimetry (DSC), X-ray diffraction studies (XRD) and IR studies. Solid state characterization of the drug β-CD binary system using XRD, FTIR and DSC revealed distinct loss of drug crystallinity in the formulation, ostensibly accounting for enhancement of dissolution rate.

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