scholarly journals Maskelynite formation via solid-state transformation: Evidence of infrared and X-ray anisotropy

2015 ◽  
Vol 120 (3) ◽  
pp. 570-587 ◽  
Author(s):  
Steven J. Jaret ◽  
William R. Woerner ◽  
Brian L. Phillips ◽  
Lars Ehm ◽  
Hanna Nekvasil ◽  
...  
Keyword(s):  
Solid State ◽  
State Transformation ◽  
Solid State Transformation ◽  
X Ray

The Effects of Cooling Rate Upon Xdt m TiAl Weld Microstructure

1990 ◽  
Vol 194 ◽  
Author(s):  
Erica Robertson ◽  
Mary Ann Hill ◽  
Ricardo B. Schwarz
Keyword(s):  
Solid State ◽  
Cooling Rate ◽  
Volume Fraction ◽  
Mechanical Test ◽  
Test System ◽  
X Ray Diffraction ◽  
State Transformation ◽  
Solid State Transformation ◽  
X Ray ◽  
Weld Microstructure

AbstractFusion zone microstructures of an electron beam (EB) welded XDt m Ti–48at%Al + 6.5 vol% TiB2 alloy revealed plate-like precipitates which were absent in the base metal. The volume fraction of this phase increased with increasing cooling rate and correlated with increased weld cracking frequency. To determine whether this phase was a product of solidification from the melt or a product of a solid-state transformation, the microstructures of the welds were compared to those of samples cycled in a Gleeble 1500/20 Thermal-Mechanical Test System which was programmed to simulate the solid-state portion of the weld cooling rates (as predicted by a Rosenthal analysis). The microstructures were characterized by X-ray diffraction, optical and by scanning electron microscopy. The plate-like phase found in the weld microstructures was identified as TiB2 occurring upon rapid solidification of the melted weld metal.

In Situ High-Energy X-Ray Diffraction Studies of Melting, Solidification and Solid-State Transformation of Ni3Sn

MRS Advances ◽  
2020 ◽  
Vol 5 (29-30) ◽  
pp. 1529-1535 ◽  
Author(s):  
Rijie Zhao ◽  
Jianrong Gao ◽  
Yang Ren
Keyword(s):  
Solid State ◽  
Elevated Temperatures ◽  
High Energy ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
State Transformation ◽  
Solid State Transformation ◽  
X Ray ◽  
Melting And Solidification

AbstractMelting, solidification and solid-state transformation of the intermetallic Ni3Sn compound were investigated in situ using synchrotron high-energy X-ray diffraction. It was observed that the compound undergoes a hexagonal to cubic transition before melting. In solidification, a disordered cubic phase crystallizes from the liquid at a large undercooling but it is reordered prior to bulk solidification. In melting and solidification, forced or natural flows are active bringing about significant changes of crystal orientations. These in situ observations provided insights into phase transformations of Ni3Sn at elevated temperatures and their roles in formation of metastable microstructure consisting of coarse grains and subgrains.

X-ray diffraction from one-dimensionally disordered 2H crystals undergoing solid state transformation to the 6H structure. III. Comparison with experimental observations on SiC

1980 ◽  
Vol 369 (1739) ◽  
pp. 463-477 ◽  
Keyword(s):  
Solid State ◽  
Deformation Mechanism ◽  
X Ray Diffraction ◽  
Fault Probability ◽  
State Transformation ◽  
Solid State Transformation ◽  
Simple Estimate ◽  
X Ray ◽  
Displacement Mechanism ◽  
Diffraction Effects

The diffraction effects predicted theoretically in the preceding two papers for 2H crystals undergoing solid state transformation to the 6H structure by the layer displacement mechanism and the deformation mechanism are compared with those experimentally observed on SiC. It is shown that the observed diffraction characteristics can be explained in terms of the layer displacement mechanism and not the deformation mechanism. A simple estimate of the layer displacement fault probability in two transformed 6H SiC crystals has been made by analysing the halfwidth of the experimentally obtained intensity profiles of the 10. L reflexions. It is also shown that the presence of a small concentration of growth faults in the as-grown 2H SiC crystal does not alter the basic diffraction characteristics predicted in part I of this series of papers.

Structures of [Pd(NH3)2 X 2] and its chemical transformation in the solid state

2000 ◽  
Vol 56 (3) ◽  
pp. 419-425 ◽  
Author(s):  
S. D. Kirik ◽  
L. A. Solovyov ◽  
A. I. Blokhin ◽  
I. S. Yakimov
Keyword(s):  
Solid State ◽  
Powder Diffraction ◽  
Molecular Structures ◽  
Structural Determination ◽  
Powder Diffraction Data ◽  
Thermal Transformations ◽  
State Transformation ◽  
Solid State Transformation ◽  
Space Group ◽  
X Ray

Crystal structures of [Pd(NH3)2 X 2] complexes, where X = Br or I, diamminediiodo-/-dibromopalladium(II), have been studied by X-ray powder diffraction. The series consists of five complexes: cis-[Pd(NH3)2Br2] (I) [a = 13.3202 (7), b = 12.7223 (6), c = 7.05854 (3) Å, Z = 8, space group Pbca], trans-[Pd(NH3)2Br2] (II) [a = 6.7854 (3), b = 7.1057 (3), c = 6.6241 (2) Å, α = 103.221 (3), β = 102.514 (2), γ = 100.386 (3)°, Z = 2, space group P\overline 1], β-trans-[Pd(NH3)2Br2] (III) [a = 8.4315 (3), b = 8.4206 (3), c = 8.0916 (2) Å, Z = 4, space group Pbca], cis-[Pd(NH3)2I2] (IV) [a = 13.9060 (8), b = 13.5035 (8), c = 7.5050 (4) Å, Z = 8, space group Pbca], and β-trans-[Pd(NH3)2I2] (V) [a = 8.8347 (5), b = 8.8410 (5), c = 8.6081 (2) Å, Z = 4, space group Pbca]. Patterson synthesis and Rietveld refinement have been used for structural determination. Molecular structures with column- or parquet-type packing of flat complexes are characteristic of these substances. Corresponding cis- and β-trans compounds are isostructural. The thermal transformations cis→trans→β-trans (cis→β-trans in the case of iodine) are considered. Cl derivatives are also discussed. The transformations proceed irreversibly and are accompanied by decreasing specific volume. Owing to these features, they can be classified as chemical reactions. High-temperature X-ray powder diffraction was used to study the transformations in air. The set of data is consistent with a solid state transformation from cis to trans. According to this model, the columns of molecules remain intact during the process, and the transformation proceeds via the breaking of Pd...X and Pd...N intermolecular bonds. The powder diffraction data have been deposited in ICDD-JCPDS (45-0596, 46-0876, 46-0879, 47-1690, 48-1185).

X-ray diffraction from one-dimensionally disordered 2H crystals undergoing solid state transformation to the 6H structure II. The deformation mechanism

1980 ◽  
Vol 369 (1739) ◽  
pp. 451-461 ◽  
Keyword(s):  
Solid State ◽  
Deformation Mechanism ◽  
Random Distribution ◽  
Exact Expression ◽  
X Ray Diffraction ◽  
State Transformation ◽  
Solid State Transformation ◽  
X Ray ◽  
Diffraction Effects ◽  
Close Packed Layer

The 2H or AB Structure may be transformed to 6H or ABCACB structure if deformation faults occur preferentially after every third close-packed layer. The theory of X-ray diffraction from one-dimensionally disordered crystals undergoing the 2H → 6H structural transformation by such a deformation mechanism is developed. For this, it is necessary to consider that the faults are not distributed entirely at random but tend to occur in such a manner as to statistically create a 6H structure. An exact expression for the diffracted intensity for crystals undergoing the 2H → 6H transformation by the deformation mechanism has been obtained and the different observable diffraction effects have been predicted. These results are very different from those obtained of 2H crystals containing an entirely random distribution of deformation faults, especially for large fault probabilities.

The NaAlSiO4 nepheline-carnegieite solid-state transformation

1994 ◽  
Vol 209 (2) ◽  
Author(s):  
H. Schneider ◽  
O. W. Flörke ◽  
R. Stoeck
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Single Crystals ◽  
Transformation Process ◽  
State Transformation ◽  
Solid State Transformation ◽  
X Ray ◽  
Thermally Activated ◽  
Transformation Mechanisms ◽  
Temperature Transformation

AbstractThe reconstructive high-temperature transformation of NaAlSiOX-ray precession patterns of single crystals heattreated between 1543 K and 1593 K yielded an oriented transformation of NaAlSiOThe oriental relationships between nepheline and carnegieite are similar to those observed in the high-temperature transformation of tridymite to cristobalite. However, the transformation mechanisms are believed to be different. Thermally activated Na and weakening of the tetrahedral Al–O-bonds produce quickly migrating non-bridging O-atoms which act as conversion nuclei, accelerating strongly the transformation process in comparison to SiO

scholarly journals Synthesis, Crystal Structure and Solid State Transformation of 1,2-Bis[(1-methyl-1H-imidazole-2-yl)thio]ethane

Crystals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 667
Author(s):  
Leo Štefan ◽  
Dubravka Matković-Čalogović ◽  
Darko Filić ◽  
Miljenko Dumić
Keyword(s):  
Solid State ◽  
Room Temperature ◽  
Water Mixture ◽  
State Transformation ◽  
Solid State Transformation ◽  
Thermal Methods ◽  
Related Substance ◽  
Space Group ◽  
X Ray ◽  
The One

The spontaneous S-alkylation of the thyreostatic drug methimazole (1-methyl-1,3-dihydro-1H-imidazole-2-thione, 1) with 1,2-dichloroethane at room temperature, in dark or light conditions, led to the formation of its related substance 1,2-bis[(1-methyl-1H-imidazole-2-yl)thio]ethane, C10H14N4S2 (2a), primarily isolated in the form of dihydrochloride tetrahydrate [C10H16N4S2]Cl2·4(H2O) (2b), which crystallized in the monoclinic P21/c space group. Neutralization of 2b, followed by crystallization from the acetone/water mixture, produced dihydrate C10H14N4S2·2(H2O) (2c), which crystallized in the trigonal R-3 space group. Six water molecules in 2c are H-bonded mutually and to the nitrogen atoms of six molecules of 2a. DSC and TGA showed that 2c melts at 65 °C and loses water up to 120 °C. By cooling to room temperature, anhydrous 2a was obtained. Single crystals of 2a that are suitable for X-ray structure analysis were obtained by neutralization of 2b, followed by crystallization from dry dichloromethane. Anhydrous 2a crystallizes in the monoclinic P21/c space group. The dehydration of 2c led to the formation of the anhydrous product 2a, which is identical to the one obtained by crystallization, as was found by complementary solid-state techniques. No intermediate monohydrate or hemihydrate phases were detected. Powder diffraction showed the same pattern of 2c via both preparation procedures. The structures of all the forms were elucidated by spectroscopy, microscopy and thermal methods and confirmed by single crystal X-ray analysis.

Sign in / Sign up

Export Citation Format

Share Document