scholarly journals Effect of HIP Parameters on the Micro-Structural Evolution of a Single Crystal Ni-Based Superalloy

2011 ◽  
Vol 278 ◽  
pp. 72-77 ◽  
Author(s):  
Inmaculada Lopez-Galilea ◽  
Stephan Huth ◽  
Marion Bartsch ◽  
Werner Theisen
Keyword(s):  
Single Crystal ◽  
Atmospheric Pressure ◽  
High Pressures ◽  
Hot Isostatic Pressing ◽  
Structural Evolution ◽  
Local Deformation ◽  
Local Distribution ◽  
Slow Cooling ◽  
Distribution Of Elements ◽  
Hardened State

For reducing the porosity of single crystal (SX) nickel-based superalloys, Hot Isostatic Pressing (HIP) is used. High pressures of about 100-170 MPa lead to local deformation, which close the pores. However, since HIP also requires high temperatures (1000-1200°C) it has a pronounced effect on the microstructure and the local distribution of elements. This contribution analyses the effect of different HIP treatments on both the microstructure and the segregation of the SX superalloy LEK94 in the as-precipitation-hardened state. In addition, the effects of rapid or slow cooling are analyzed. To distinguish the effect of pressure from those of temperature, the HIPed samples are compared with specimens annealed at atmospheric pressure.

Estimation of polyhedral compressibilities and structural evolution of GdFeO3-type perovskites at high pressures

2006 ◽  
Vol 62 (3) ◽  
pp. 431-439 ◽  
Author(s):  
J. Zhao ◽  
N. L. Ross ◽  
R. J. Angel
Keyword(s):  
High Pressure ◽  
Single Crystal ◽  
High Pressures ◽  
Structural Evolution ◽  
Structural Data ◽  
New Approach ◽  
Cell Parameters ◽  
Pressure Unit ◽  
Crystal Structural Data ◽  
Crystal Structural

A new approach based on the bond-valence matching relation is developed to predict the detailed structural evolution of GdFeO3-type perovskites at high pressure from knowledge of the room-pressure structure and the high-pressure unit-cell parameters alone. The evolution of perovskite structures estimated in this way is in good agreement with the structure refinements available from high-pressure single-crystal diffraction measurements of a number of perovskites. The method is then extended to predict the structure of MgSiO3 perovskite at pressures for which no single-crystal structural data are available and the results are compared to ab initio quantum calculations of MgSiO3 perovskite up to 120 GPa.

Microstructure and reactivity of small metal particles: The role of Ce additives

1992 ◽  
Vol 50 (1) ◽  
pp. 318-319
Author(s):  
L.D. Schmidt ◽  
K. R. Krause ◽  
J. M. Schwartz ◽  
X. Chu
Keyword(s):  
Atmospheric Pressure ◽  
Noble Metals ◽  
Mixed Oxides ◽  
Catalytic Properties ◽  
Chemical Shifts ◽  
Catalytic Converter ◽  
Structural Evolution ◽  
Single Particles ◽  
Small Metal Particles

The evolution of microstructures of 10- to 100-Å diameter particles of Rh and Pt on SiO2 and Al2O3 following treatment in reducing, oxidizing, and reacting conditions have been characterized by TEM. We are able to transfer particles repeatedly between microscope and a reactor furnace so that the structural evolution of single particles can be examined following treatments in gases at atmospheric pressure. We are especially interested in the role of Ce additives on noble metals such as Pt and Rh. These systems are crucial in the automotive catalytic converter, and rare earths can significantly modify catalytic properties in many reactions. In particular, we are concerned with the oxidation state of Ce and its role in formation of mixed oxides with metals or with the support. For this we employ EELS in TEM, a technique uniquely suited to detect chemical shifts with ∼30Å resolution.

Growth of Single-Crystal Pyrite Films by Atmospheric Pressure Chemical Vapor Deposition

2003 ◽  
Vol 15 (9) ◽  
pp. 1763-1765 ◽  
Author(s):  
Naoyuki Takahashi ◽  
Yusuke Nakatani ◽  
Takuma Yatomi ◽  
Takato Nakamura
Keyword(s):  
Chemical Vapor Deposition ◽  
Single Crystal ◽  
Vapor Deposition ◽  
Atmospheric Pressure ◽  
Chemical Vapor ◽  
Pressure Chemical

Monoclinic FeO at high pressures

2008 ◽  
Vol 223 (7/2008) ◽  
Author(s):  
Innokenty Kantor ◽  
Alexander Kurnosov ◽  
Catherine McCammon ◽  
Leonid Dubrovinsky
Keyword(s):  
High Pressure ◽  
Iron Oxide ◽  
Single Crystal ◽  
Diffraction Study ◽  
High Pressures ◽  
X Ray Diffraction ◽  
X Ray

AbstractA high-pressure quasi-single crystal X-ray diffraction study of a synthetic iron oxide Fe

scholarly journals Epitaxial Growth of Magnesia Films on Single Crystalline Magnesia Substrates by Atmospheric-Pressure Chemical Vapor Deposition

2016 ◽  
Vol 5 (2) ◽  
pp. 56
Author(s):  
Keiji Komatsu ◽  
Pineda Marulanda David Alonso ◽  
Nozomi Kobayashi ◽  
Ikumi Toda ◽  
Shigeo Ohshio ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Single Crystal ◽  
Vapor Deposition ◽  
Atmospheric Pressure ◽  
Reciprocal Lattice ◽  
Chemical Vapor ◽  
X Ray ◽  
Pole Figures ◽  
Out Of Plane ◽  
Pressure Chemical

<p class="1Body">MgO films were epitaxially grown on single crystal MgO substrates by atmospheric-pressure chemical vapor deposition (CVD). Reciprocal lattice mappings and X-ray reflection pole figures were used to evaluate the crystal quality of the synthesized films and their epitaxial relation to their respective substrates. The X-ray diffraction profiles indicated that the substrates were oriented out-of-plane during MgO crystal growth. Subsequent pole figure measurements showed how all the MgO films retained the substrate in-plane orientations by expressing the same pole arrangements. The reciprocal lattice mappings indicated that the whisker film showed a relatively strong streak while the continuous film showed a weak one. Hence, highly crystalline epitaxial MgO thin films were synthesized on single crystal MgO substrates by atmospheric-pressure CVD.</p>

scholarly journals Simulation of the External Pressure Influence on the Micro-Structural Evolution of a Single Crystal Ni-Based Superalloy

2011 ◽  
Vol 278 ◽  
pp. 247-252
Author(s):  
Inmaculada Lopez-Galilea ◽  
Stephan Huth ◽  
Suzana Gomes Fries ◽  
Ingo Steinbach ◽  
Werner Theisen
Keyword(s):  
Single Crystal ◽  
Microstructural Evolution ◽  
Phase Field ◽  
Structural Evolution ◽  
Field Method ◽  
External Pressure ◽  
Experimental Results ◽  
Alloying Elements ◽  
Phase Field Method

The phase field method has been applied to simulate the microstructural evolution of a commercial single crystal Ni-based superalloy during both, HIP and annealing treatments. The effects of applying high isostatic pressure on the microstructural evolution, which mainly retards the diffusion of the alloying elements causing the loss of the orientational coherency between the phases is demonstrated by the simulation and experimental results

Microstructural Characterization of High-Pressure Oxidized Si1-x Gex /Si Heterolayers

1992 ◽  
Vol 280 ◽  
Author(s):  
N. David Theodore ◽  
Gordon Tam
Keyword(s):  
Heterojunction Bipolar Transistors ◽  
Atmospheric Pressure ◽  
High Pressures ◽  
Microstructural Characterization ◽  
Bipolar Transistors ◽  
Pure Silicon ◽  
Device Structures ◽  
Microstructural Behavior ◽  
Very High

ABSTRACTSiGe alloys have recently been of interest for fabrication of heterojunction bipolar transistors using pre-existing or modified silicon-processing technology. These devices are faster than devices using pure silicon. Because of the interest in developing SiGe device structures, various elements of processing relevant to fabrication of the devices are being investigated. One such element has been the use of thermal oxidation for isolation of SiGe devices. Utilization of the technique requires an understanding of oxidation behavior of SiGe layers under a variety of oxidation conditions. Past studies in the literature have investigated the oxidation of SiGe at atmospheric pressure or at very high pressures (∼650–1300 atmospheres). The present study investigates the wet-oxidation of SiGe structures at intermediate pressures (∼25 atmospheres) and temperatures (∼750°C). Unlike atmospheric oxidation, most of the Ge (from SiGe) remains in the oxidized silicon (SiO2) in the form of GeO2. Occasional segregation of Ge to the oxidizing interface is noted. The microstructural behavior of partially and entirely oxidized structures is presented.

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