Effects of Non-Equilibrium Solidification and Aging Treatment on Microstructure Characteristic of a Ni-Base Superalloy

Copper mould spray casting and aging treatment were performed to investigate the microstructure evolution of a Ni-base superalloy. With increasing the cooling rate during solidification, the morphology of primary γ phase changes from coarse dendrite to fine dendritic structure with radial-like feature, accompanied by the inhibition of γ′ phase due to the shortened period during the subsequent solid state transformation process. After aging treatment, both the size and volume fraction of γ′ phase are increased with prolonging the isothermal time, which generate the morphology transition of precipitates from irregular and spherical to ellipse and rectangle due to the competition between the interface energy and strain energy.

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The Effects of Cooling Rate Upon Xdt m TiAl Weld Microstructure

MRS Proceedings ◽

10.1557/proc-194-113 ◽

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.

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Electron microscopic study of the illite–smectite transformation in the bentonites from Cerro del Aguila (Toledo, Spain)

Clay Minerals ◽

10.1180/000985598545660 ◽

1998 ◽

Vol 33 (3) ◽

pp. 501-510 ◽

Cited By ~ 6

Author(s):

C. de Santiago Buey ◽

M. Suarez Barrios ◽

E. Garcia Romero ◽

M. C. Dominguez Diaz ◽

M. Doval Montoya

Keyword(s):

Layer Structure ◽

Interlayer Spacing ◽

Transformation Process ◽

Raw Material ◽

State Transformation ◽

Solid State Transformation ◽

Electron Microscopic ◽

Sem And Tem ◽

Trioctahedral Smectite ◽

Weathering Process

AbstractA mineralogical and microstructural study of bentonites from 'Cerro del Aguila' located in the Tagus Basin (Toledo, Spain) was carried out using XRD, SEM and TEM observations and chemical data obtained by TEM-EDX. The bentonites are mainly composed of trioctahedral smectite with a unit-cell formula (Si3.76Al0.24)(Al0.44Fe3+0.26Mg1.81)Ca0.05K0.19O10(OH)2 and small amounts of illite. The relationships between illite and smectite particles observed by SEM and TEM allowed the study of the weathering process of illite to form smectite through possible intermediate stages. The transformation begins as an exfoliation normal to the stacking direction and develops by opening of the interlayer spacing, the replacement of K+ by hydrated interlayer cations and slight reorganization of the 2:1 layer structure. The so-called solid-state transformation process then proceeds by further dissolution and the formation of a colloidal phase acting as raw material in the growth of new phyllosilicates such as smectite.

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Mo Effect on the Microstructure in Co-Al-W-Based Superalloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.420 ◽

2010 ◽

Vol 654-656 ◽

pp. 420-423 ◽

Cited By ~ 12

Author(s):

Fei Xue ◽

Zhi Qiang Li ◽

Qiang Feng

Keyword(s):

Solution Treatment ◽

Aging Treatment ◽

Eutectic Structure ◽

Phase Precipitation ◽

State Transformation ◽

Solid State Transformation ◽

Heat Treated ◽

Cast Alloys ◽

Do19 Phase ◽

Mo Effect

The as-cast and heat-treated microstructure has been investigated in Co-Al-W-based superalloys with additions of 2 and 4 at.% Mo. The results revealed that Mo promoted the formation of (μ+γ) eutectic structure in the as-cast alloys and μ-phase precipitation after solution treatment. In addition, after aging treatment at 900oC, an extensive network of DO19 precipitates was observed, besides the γ+γ′ primary phases and the μ phase inherited from the as-cast and solution-treated conditions. Meanwhile, a solid-state transformation from the μ phase to the DO19 phase occurred; and long-term aging enhanced this transformation. In addition, high levels of Mo promoted the DO19-phase precipitation.

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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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Some Considerations Concerning the Differential Scanning Calorimetry of Ultra Tough Plastic Materials

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.659.107 ◽

2014 ◽

Vol 659 ◽

pp. 107-111

Author(s):

Dumitru Nedelcu ◽

Nicoleta Monica Lohan ◽

Constantin Carausu ◽

Octavian Pruteanu

Keyword(s):

Differential Scanning Calorimetry ◽

Heat Flow ◽

Reference Value ◽

Test Sample ◽

Transformation Process ◽

State Transformation ◽

Solid State Transformation ◽

Scanning Calorimetry ◽

Flow Variation ◽

Plastic Materials

The Differential Scanning Calorimetry (DSC) it’s an important analysis in research since the 20thcentury, being used is various fields such as: physics, chemistry, science and materials technology. Its applicability has also extended to other fields, such as nanothermodynamics and bio-thermodynamics. Calorimetry measures the amount of heat absorbed/dissipated by a test sample as compared to a reference value, when the test sample is subjected to a heating and/or cooling cycle. The calorimetric effect may be revealed by the temperature-and/or time-dependent heat flow variation, and its evaluation makes sense when particular heat flow variations, specific to the various transformations accompanying temperature variation, occur. The research described in this paper focuses on the study of calorimetry of ultra tough plastic materials such B4300G4 and B4300G6. The samples were obtained by injection moulding and the planning of the experiments was achieved by means of the Taguchi methodology. The differential scanning calorimetry will show the endothermal and exothermal transformations during which we measured the transformation onset and completion temperatures, as well as the temperature in the middle of the transformation process. Also will be measured the amount of absorbed and dissipated heat, respectively. The DSC diagram showed no temperature-dependent heat flow variation that could suggest a solid state transformation. This paper aims to highlight the behavior of glass transition using DSC analysis, the transformation that occurs during heating of the two polymers obtained using three injection angles: 0o, 45oand 90o.

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Solid-State Transformation from Self-Assembled Nanosheets into Ordered Nanorods

The Journal of Physical Chemistry B ◽

10.1021/jp0561367 ◽

2006 ◽

Vol 110 (9) ◽

pp. 4054-4057 ◽

Cited By ~ 7

Author(s):

Sanjit Konar ◽

Z. Ryan Tian

Keyword(s):

Solid State ◽

State Transformation ◽

Solid State Transformation ◽

Self Assembled

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Effects of Deformation Mode on Resistivity Curve Used for Estimating Martensite Induced in Stainless Steel

Materials Science Forum ◽

10.4028/www.scientific.net/msf.638-642.2992 ◽

2010 ◽

Vol 638-642 ◽

pp. 2992-2997 ◽

Cited By ~ 3

Author(s):

Hidefumi Date

Keyword(s):

Stainless Steel ◽

Austenitic Stainless Steel ◽

Linear Relation ◽

Volume Fraction ◽

Tensile Deformation ◽

Deformation Mode ◽

Transformation Process ◽

Martensite Formation ◽

Austenitic Phase ◽

Ε Phase

The martensite induced in three types of austenitic stainless steel, which indicate the different stability of the austenitic phase (γ), were estimated by the resistivity measured during the tensile deformation or compressive deformation at the temperatures 77, 187 and 293 K. The resistivity curves were strongly dependent on the deformation mode. The volume fraction of the martensite (α’) was also affected by the deformation mode. The ε phase, which is the precursor of the martensite and is induced from the commencement of the deformation, decreased the resistivity. However, lots of defects generated by the deformation-induced martensite increased the resistivity. The experimental facts and the results shown by the modified parallelepiped model suggested a complicated transformation process depending on each deformation mode. The results shown by the model also suggested a linear relation between the resistivity and the martensite volume at the region of the martensite formation. The fact denoted that the resistivity is mostly not controlled by the austenite, ε phase and martensite, but by the defects induced due to the deformation-induced martensite.

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