X-ray diffraction study of the 2H to 3C solid state transformation in vapour grown single crystals of ZnS

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.

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

MRS Advances ◽

10.1557/adv.2020.22 ◽

2020 ◽

Vol 5 (29-30) ◽

pp. 1529-1535 ◽

Cited By ~ 1

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.

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X-Ray Diffraction from a Sic Crystal Undergoing the 3C–6H Solid State Transformation by Non-Random Microtwinning

phys stat sol (a) ◽

10.1002/pssa.2210840207 ◽

1984 ◽

Vol 84 (2) ◽

pp. 401-409 ◽

Cited By ~ 8

Author(s):

M. T. Sebastiak ◽

P. Krishna

Keyword(s):

Solid State ◽

X Ray Diffraction ◽

State Transformation ◽

Solid State Transformation ◽

X Ray

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

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1980.0011 ◽

1980 ◽

Vol 369 (1739) ◽

pp. 463-477 ◽

Cited By ~ 16

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.

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

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1980.0010 ◽

1980 ◽

Vol 369 (1739) ◽

pp. 451-461 ◽

Cited By ~ 13

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.

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The NaAlSiO4 nepheline-carnegieite solid-state transformation

Zeitschrift für Kristallographie - Crystalline Materials ◽

10.1524/zkri.1994.209.2.113 ◽

1994 ◽

Vol 209 (2) ◽

Cited By ~ 6

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

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