Homogenizing a Nickel-Based Superalloy: Thermodynamic and Kinetic Simulation and Experimental Results

2009 ◽  
Vol 40 (2) ◽  
pp. 182-186 ◽  
Author(s):  
Paul D. Jablonski ◽  
Christopher J. Cowen
Keyword(s):  
Experimental Results ◽  
Kinetic Simulation ◽  
Nickel Based Superalloy

Homogenisation of Cast Microstructures: Thermodynamic Calculation and Kinetic Simulation

2010 ◽  
Vol 654-656 ◽  
pp. 1532-1535
Author(s):  
Zhan Li Guo ◽  
Alfred Peter Miodownik ◽  
Rong Shan Qin
Keyword(s):  
Concentration Profile ◽  
Thermodynamic Calculation ◽  
Solute Concentration ◽  
Solute Segregation ◽  
Kinetic Simulation ◽  
Secondary Phases ◽  
Nickel Based Superalloy ◽  
Segregation Profile ◽  
Type Calculation ◽  
Homogenisation Process

This paper uses a combination of thermodynamic calculation and kinetic simulation to model the homogenisation process of cast microstructure for multi-component alloys. The approach assumes that the solute segregation profile across the half dendrite arm spacing can be scaled to the solute concentration profile during solidification as generated by a Scheil type calculation. When secondary phases dissolve during homogenisation, they are treated as an additional fraction of pseudo-eutectic to the initial solute concentration profile of the primary solution phase. The methodology is compared with the assumptions made by other authors, highlighting the significant advantages in the present treatment. Examples are drawn from a cast nickel-based superalloy.

Study on Erosion-Resistance of Electro-Thermal Explosion Ultra-High Speed Spraying MoSi2-Based Coatings

2008 ◽  
Vol 33-37 ◽  
pp. 1271-1276
Author(s):  
Shi Xiang Hou ◽  
Zong De Liu ◽  
Dong Yu Liu ◽  
Li Ping Zhao ◽  
Yi Min Ma
Keyword(s):  
Thermal Explosion ◽  
High Speed ◽  
Erosion Resistance ◽  
Experimental Results ◽  
Erosion Wear ◽  
Nickel Based Superalloy ◽  
Ultra High Speed ◽  
Phase Coating ◽  
Better Than

A new method, electro-thermal explosion ultra-high speed spraying, was utilized to produce the Mo-Si or Mo-Si-B coatings. Experimental results showed that submicron-grain pure MoSi2 phase coating and boron alloyed MoSi2-MoB2 multiphase coatings were in-situ synthesized on GH3039 nickel-based superalloy substrate. Erosion-resistance test of GH3039 nickel-based superalloy and MoSi2-based coatings were performed under high temperature(800°C) with GW/CS – MS erosion wear tester. Quartz sand was employed as erosive material. Experimental results showed that the erosion-resistance of the MoSi2-based coatings is better than that of the GH3039 nickel-based superalloy.

Diagnostics of Gold Laser Plasmas

1988 ◽  
Vol 102 ◽  
pp. 357-360
Author(s):  
J.C. Gauthier ◽  
J.P. Geindre ◽  
P. Monier ◽  
C. Chenais-Popovics ◽  
N. Tragin ◽  
...  
Keyword(s):  
Experimental Results ◽  
Pure Gold ◽  
Electronic Temperature ◽  
X Ray ◽  
Laser Plasmas ◽  
Collisional Radiative Model ◽  
Radiative Model

AbstractIn order to achieve a nickel-like X ray laser scheme we need a tool to determine the parameters which characterise the high-Z plasma. The aim of this work is to study gold laser plasmas and to compare experimental results to a collisional-radiative model which describes nickel-like ions. The electronic temperature and density are measured by the emission of an aluminium tracer. They are compared to the predictions of the nickel-like model for pure gold. The results show that the density and temperature can be estimated in a pure gold plasma.

Observation of Phase Contrast Images in STEM and CTEM Modes by Using 100 kV Field Emission Electron Gun

1974 ◽  
Vol 32 ◽  
pp. 390-391
Author(s):  
Y. Harada ◽  
T. Goto ◽  
H. Koike ◽  
T. Someya
Keyword(s):  
Field Emission ◽  
Phase Contrast ◽  
Image Formation ◽  
Fresnel Diffraction ◽  
Experimental Results ◽  
Electron Gun ◽  
Scanning Microscopy ◽  
Emission Electron ◽  
Lattice Images

Since phase contrasts of STEM images, that is, Fresnel diffraction fringes or lattice images, manifest themselves in field emission scanning microscopy, the mechanism for image formation in the STEM mode has been investigated and compared with that in CTEM mode, resulting in the theory of reciprocity. It reveals that contrast in STEM images exhibits the same properties as contrast in CTEM images. However, it appears that the validity of the reciprocity theory, especially on the details of phase contrast, has not yet been fully proven by the experiments. In this work, we shall investigate the phase contrast images obtained in both the STEM and CTEM modes of a field emission microscope (100kV), and evaluate the validity of the reciprocity theory by comparing the experimental results.

A new dissociation mode for dislocations in silicon

1978 ◽  
Vol 36 (1) ◽  
pp. 346-347
Author(s):  
A. Ourmazd ◽  
G.R. Booker ◽  
C.J. Humphreys
Keyword(s):  
Detailed Examination ◽  
Experimental Results ◽  
Dislocation Network ◽  
Weak Beam ◽  
Phosphorus Doped

A (111) phosphorus-doped Si specimen, thinned to give a TEM foil of thickness ∼ 150nm, contained a dislocation network lying on the (111) plane. The dislocation lines were along the three <211> directions and their total Burgers vectors,ḇt, were of the type , each dislocation being of edge character. TEM examination under proper weak-beam conditions seemed initially to show the standard contrast behaviour for such dislocations, indicating some dislocation segments were undissociated (contrast A), while other segments were dissociated to give two Shockley partials separated by approximately 6nm (contrast B) . A more detailed examination, however, revealed that some segments exhibited a third and anomalous contrast behaviour (contrast C), interpreted here as being due to a new dissociation not previously reported. Experimental results obtained for a dislocation along [211] with for the six <220> type reflections using (g,5g) weak-beam conditions are summarised in the table below, together with the relevant values.

Multislice calculations of RHEED patterns from vicinal Si (001)

1993 ◽  
Vol 51 ◽  
pp. 1000-1001
Author(s):  
Scott Lordi
Keyword(s):  
Misorientation Angle ◽  
Incident Angle ◽  
Incident Beam ◽  
Experimental Results ◽  
Bragg Condition ◽  
Vicinal Surfaces ◽  
Kinematic Theory ◽  
Step Edges

Vicinal Si (001) surfaces are interesting because they are good substrates for the growth of III-V semiconductors. Spots in RHEED patterns from vicinal surfaces are split due to scattering from ordered step arrays and this splitting can be used to determine the misorientation angle, using kinematic arguments. Kinematic theory is generally regarded to be inadequate for the calculation of RHEED intensities; however, only a few dynamical RHEED simulations have been attempted for vicinal surfaces. The multislice formulation of Cowley and Moodie with a recently developed edge patching method was used to calculate RHEED patterns from vicinal Si (001) surfaces. The calculated patterns are qualitatively similar to published experimental results and the positions of the split spots quantitatively agree with kinematic calculations.RHEED patterns were calculated for unreconstructed (bulk terminated) Si (001) surfaces misoriented towards [110] ,with an energy of 15 keV, at an incident angle of 36.63 mrad ([004] bragg condition), and a beam azimuth of [110] (perpendicular to the step edges) and the incident beam pointed down the step staircase.

Appropriation des Savoirs et Mémoire Collective

2013 ◽  
Vol 72 (2) ◽  
pp. 71-78
Author(s):  
Sophie Richardot
Keyword(s):  
Collective Memory ◽  
Factorial Analysis ◽  
Experimental Results ◽  
Ancient History ◽  
Historical Events ◽  
Memoire Collective ◽  
Obedience To Authority

The aim of this study is to understand to what extent soliciting collective memory facilitates the appropriation of knowledge. After being informed about Milgram’s experiment on obedience to authority, students were asked to mention historical or contemporary events that came to mind while thinking about submission to authority. Main results of the factorial analysis show that the students who do not believe in the reproducibility of the experimental results oppose dramatic past events to a peaceful present, whereas those who do believe in the reproducibility of the results also mention dramatic contemporary events, thus linking past and present. Moreover, the students who do not accept the results for today personify historical events, whereas those who fully accept them generalize their impact. Therefore, according to their attitude toward this objet of knowledge, the students refer to two kinds of memory: a “closed memory,” which tends to relegate Milgram’s results to ancient history; and an “open memory,” which, on the contrary, transforms past events into a concept that helps them understand the present. Soliciting collective memory may contribute to the appropriation of knowledge provided the memory activated is an “open” one, linking past to present and going beyond the singularity of the event.

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