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.

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.

scholarly journals Synthesis of a novel hybrid metal–organic salt and its solid-state transformation

2014 ◽  
Vol 38 (4) ◽  
pp. 1385-1388 ◽  
Author(s):  
Javier Martí-Rujas ◽  
Massimo Cametti
Keyword(s):  
Solid State ◽  
Metal Cluster ◽  
Organic Salt ◽  
X Ray Diffraction ◽  
State Transformation ◽  
Solid State Transformation ◽  
X Ray ◽  
Metal Organic

A new adamantanoid metal cluster has been synthesized and its solid-state transformation monitored by X-ray diffraction.

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

scholarly journals Discovery of natural MgSiO3tetragonal garnet in a shocked chondritic meteorite

2016 ◽  
Vol 2 (3) ◽  
pp. e1501725 ◽  
Author(s):  
Naotaka Tomioka ◽  
Masaaki Miyahara ◽  
Motoo Ito
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Solid State ◽  
Electron Diffraction ◽  
Cooling Rate ◽  
Upper Bound ◽  
Cation Ordering ◽  
State Transformation ◽  
Solid State Transformation ◽  
Shock Temperature

MgSiO3tetragonal garnet, which is the last of the missing phases of experimentally predicted high-pressure polymorphs of pyroxene, has been discovered in a shocked meteorite. The garnet is formed from low-Ca pyroxene in the host rock through a solid-state transformation at 17 to 20 GPa and 1900° to 2000°C. On the basis of the degree of cation ordering in its crystal structure, which can be deduced from electron diffraction intensities, the cooling rate of the shock-induced melt veins from ~2000°C was estimated to be higher than 103°C/s. This cooling rate sets the upper bound for the shock-temperature increase in the bulk meteorite at ~900°C.

The Morphology and Content of δ Ferrite in Non-Equilibrium Solidified 0Cr18Ni9 Austenitic Stainless Steel

2012 ◽  
Vol 535-537 ◽  
pp. 666-669
Author(s):  
Li Juan Shen ◽  
Yong Lin Ma ◽  
Shu Qing Xing
Keyword(s):  
Stainless Steel ◽  
Solid State ◽  
Austenitic Stainless Steel ◽  
Cooling Rate ◽  
State Transformation ◽  
Solid State Transformation ◽  
Circulating Water ◽  
Δ Ferrite ◽  
Non Equilibrium

The microsructural and content of δ ferrite in non-equilibrium solidified 0Cr18Ni9 austenitic stainless steel is studied by the coin with the circulating water. The solidified microstructure of the residual δ ferrite in different cooling rate is that during the course of solid-state transformation, austenite grows into ferrite gradually; corresponding to the increase of cooling rate, the microsructural of ferrite is skeletal, network, strip and block. The experiment demonstrates that the content of the residual δ ferrite is increase under the increase of the cooling rate.

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