Microstructure Observation of Inconel Alloy 617 Creep-Tested in He Environment at 950°C

2010 ◽  
Author(s):  
Gyeong-Geun Lee ◽  
Woo-Gon Kim ◽  
Yong-Wan Kim ◽  
Ji Yeon Park
Keyword(s):  
Nuclear Reactors ◽  
Bulk Diffusion ◽  
International Forum ◽  
Alloy 617 ◽  
Inconel Alloy ◽  
Microstructure Observation ◽  
Intermediate Heat Exchanger ◽  
The Matrix ◽  
Creep Time ◽  
Very High

The very high temperature gas reactor (VHTR) has been chosen by the Generation IV International Forum as one of the next-generation nuclear reactors. Due to the high operating temperatures of VHTR, Inconel alloy 617 is being considered as a primary candidate material for the intermediate heat exchanger (IHX) of the VHTR. In this study, the microstructures of creep specimens under various creep loads in a He environment were investigated. As the creep time increased, the thickness of Cr-oxide on the outer layer of the specimens clearly increased, and delaminated after a long creep time. Depths of the decarburized zones in the specimens increased slowly with creep time. However, precipitates at grain boundaries near the surface disappeared before the bulk diffusion of Cr in the matrix. It is considered that decarburization caused by minor gas impurities in He caused the reduction in creep rupture time.

Investigation of Thermophysical and Nuclear Properties of Prospective Coolants for Generation-IV Nuclear Reactors

2013 ◽  
Author(s):  
Alexey Dragunov ◽  
Eugene Saltanov ◽  
Igor Pioro ◽  
Brian Ikeda ◽  
Marija Miletic ◽  
...  
Keyword(s):  
High Temperature ◽  
Fast Reactor ◽  
Nuclear Reactors ◽  
Molten Salt Reactor ◽  
International Forum ◽  
Very High Temperature Reactor ◽  
High Temperature Reactor ◽  
Design Options ◽  
Supercritical Water Cooled Reactor ◽  
Very High

Recently, a group of countries has initiated an international collaboration, the Generation IV International Forum (GIF), to develop the next-generation nuclear reactors. The GIF program has narrowed the design options of nuclear reactors to the following six concepts: 1) SuperCritical-Water-cooled Reactor (SCWR); 2) Sodium-cooled Fast Reactor (SFR); 3) Lead-cooled Fast Reactor (LFR); 4) Molten Salt Reactor (MSR); 5) Gas-cooled Fast Reactor (GFR); and 6) Very-High-Temperature Reactor (VHTR); The purpose of this paper is to compare main thermophysical, corrosion, and neutronic properties of the Generation-IV reactors’ coolants within the proposed range of operation.

Dislocation structures around SiO2 Particles in aged Cu-Cr-SiO2

1978 ◽  
Vol 36 (1) ◽  
pp. 594-595
Author(s):  
N.J. Long ◽  
M.H. Loretto ◽  
C.H. Lloyd
Keyword(s):  
Flow Stress ◽  
Single Crystals ◽  
Room Temperature ◽  
Thin Foil ◽  
Age Hardening ◽  
Dispersion Strengthening ◽  
Accurate Picture ◽  
The Matrix ◽  
Very High ◽  
Good Agreement

IntroductionThere have been several t.e.m. studies (1,2,3,4) of the dislocation arrangements in the matrix and around the particles in dispersion strengthened single crystals deformed in single slip. Good agreement has been obtained in general between the observed structures and the various theories for the flow stress and work hardening of this class of alloy. There has been though some difficulty in obtaining an accurate picture of these arrangements in the case when the obstacles are large (of the order of several 1000's Å). This is due to both the physical loss of dislocations from the thin foil in its preparation and to rearrangement of the structure on unloading and standing at room temperature under the influence of the very high localised stresses in the vicinity of the particles (2,3).This contribution presents part of a study of the Cu-Cr-SiO2 system where age hardening from the Cu-Cr and dispersion strengthening from Cu-Sio2 is combined.

Da eine oder mehrere betroffen …

2020 ◽  
Vol 48 (1) ◽  
pp. 47-100
Author(s):  
Melitta Gillmann
Keyword(s):  
High Frequency ◽  
Formal Language ◽  
Subordinate Clause ◽  
Matrix Clause ◽  
Very High Frequency ◽  
Corpus Study ◽  
Causal Relations ◽  
Legal Texts ◽  
The Matrix ◽  
Very High

AbstractBased on a corpus study conducted using the GerManC corpus (1650–1800), the paper sketches the functional and sociosymbolic development of subordinate clause constructions introduced by the subjunctor da ‘since’ in different text genres. In the second half of the 17th and the first half of the 18th century, the da clauses were characterized by semantic vagueness: Besides temporal, spatial and causal relations, the subjunctor established conditional, concessive, and adversative links between clauses. The corpus study reveals that different genres are crucial to the readings of da clauses. Spatial and temporal usages, for example, occur more often in sermons than in other genres. The conditional reading, in contrast, strongly tends to occur in legal texts, where it displays very high frequency. This could be the reason why da clauses carry indexical meaning in contemporary German and are associated with formal language. Over the course of the 18th century, the causal usages increase in all genres. Surprisingly, these causal da clauses tend to be placed in front of the matrix clause despite the overall tendency of causal clauses to follow the matrix clause.

The Relationship Between Magnetism and Microstructure of Ethylene Pyrolysis Furnace Tubes after a Long-term Service

2018 ◽  
Vol 24 (5) ◽  
pp. 478-487 ◽  
Author(s):  
Jingfeng Guo ◽  
Tieshan Cao ◽  
Congqian Cheng ◽  
Xianming Meng ◽  
Jie Zhao
Keyword(s):  
Saturation Magnetization ◽  
Outer Region ◽  
Cr Content ◽  
Pyrolysis Furnace ◽  
The Matrix ◽  
Furnace Tube ◽  
Primary Carbides ◽  
The Relationship ◽  
Very High

AbstractThe magnetism and microstructure of Cr25Ni35Nb and Cr35Ni45Nb alloy tubes after 5 years of service were investigated in this paper. The saturation magnetization of the Cr25Ni35Nb alloy tube in the thickness direction is more than 20 emu/g, and the tube becomes ferromagnetic. The inner and outer walls of Cr35Ni45Nb alloy tubes also become ferromagnetic. But the saturation magnetization of the Cr35Ni45Nb alloy tubes approaches to zero in the center zone. The primary carbides M7C3 and NbC are changed into M23C6 and G phase at the outer region of the furnace tube. However, the M23C6-type carbides were replaced by carbon-rich carbides M7C3 at the carburization zone. Cr-depleted zones are formed at the inner and outer walls of the furnace tubes owing to oxidation. Carburization and oxidation reduce the Cr content of the matrix. Accordingly, the saturation magnetization is very high at the carburization zone and Cr-depleted zone. The magnetism of Cr25Ni35Nb and Cr35Ni45Nb alloy tubes has a high correlation with the Cr content of the matrix. Carburization and oxidation are the main reasons that make the paramagnetic ethylene pyrolysis furnace tube change to ferromagnetic.

Cropped Steel Fiber Reinforced Chemically Bonded Ceramic (CBC) Composites

1987 ◽  
Vol 114 ◽  
Author(s):  
Sean Wise ◽  
Kevan Jones ◽  
Claudio Herzfeld ◽  
David D. Double
Keyword(s):  
Silica Fume ◽  
Steel Fiber ◽  
High Strength ◽  
Cement Matrix ◽  
Metal Fiber ◽  
Morphological Form ◽  
The Matrix ◽  
Compressive And Flexural Strengths ◽  
Equivalent Properties ◽  
Very High

ABSTRACTVery high strength castable chemically bonded ceramic (CBC) materials have been prepared which consist of finely chopped steel fibers and steel aggregate in a silica modified portland cement matrix. This paper examines the effect of metal fiber addition on compressive and flexural strengths. The overall chemistry of the matrix is held constant but the morphological form of silica used and the cure conditions are altered to examine their effect. Compressive strengths in excess of 500 MPa and flexural strengths in excess of 80 MPa can be obtained.It is found that flexural strength increases proportionally with fiber content over the range of 0 to 10% by volume. Compressive strengths are not affected. Use of silica fume in the mixes produces higher strengths at low temperatures than mixes which contain only crystalline silica. High temperature curing/drying (400°C), which produces the highest strengths, produces equivalent properties for formulations with and without silica fume. Higher water/cement ratios are found to reduce compressive strengths but have relatively little effect on the flexural properties.

Microstructure and Tensile Deformation Features of Tandem Hot Rolling GH4169 Superalloy

2014 ◽  
Vol 33 (2) ◽  
pp. 131-136
Author(s):  
Zhenrong Li ◽  
Chunlei Ma ◽  
Sugui Tian ◽  
Liqing Chen ◽  
Xianghua Liu
Keyword(s):  
Hot Rolling ◽  
Tensile Deformation ◽  
Solution Treatment ◽  
Microstructure Observation ◽  
Large Numbers ◽  
Initiation And Propagation ◽  
The Matrix ◽  
Deformation Features ◽  
Δ Phase ◽  
Property Measurement

AbstractBy means of solution treatment, microstructure observation and mechanical property measurement, the microstructure and tensile deformation features of tandem hot rolling GH4169 alloy have been investigated. Results shown that, after solution treatment and aging, large numbers of the spherical γ′ phase and the flat-ellipsoidal γ″ phase dispersedly precipitate in the matrix, and acicular or short rod-like δ-phase discontinuously distribute along grain boundaries. As the tensile temperatures increases, the tensile strength and yield strength of the alloy gradually decrease. The tensile deformation features of the alloy are that the twinning and slipping dislocations with double orientations are activated in the matrix. In the later tension, the deformed dislocations pile up near the grain boundary to induce initiation and propagation of cracks due to stress concentration.

Toughness of ECC Evaluated by Nominal Fracture Energy

2012 ◽  
Vol 238 ◽  
pp. 57-60 ◽  
Author(s):  
Shu Ling Gao ◽  
Wei Shao ◽  
Jin Li Qiao ◽  
Ling Wang
Keyword(s):  
Glass Fiber ◽  
Fracture Energy ◽  
Steel Fiber ◽  
Volume Ratio ◽  
Fiber Glass ◽  
Fiber Volume ◽  
High Durability ◽  
The Matrix ◽  
Pva Fiber ◽  
Very High

ECC (Engineered Cementitious Composites) has ultra-high toughness and can be used in the zone needing the ultra-high tensile strain and very high durability. In order to investigate the toughness of ECC, the normal fracture energy GFis calculated and compared with ordinary concrete. The influence of the matrix (fly ash, silicon fume), the fiber (glass fiber, steel fiber and PVA fiber) and the fiber volume ratio on the GFof ECC are analyzed. The research indicates that silicon fume and glass fiber, steel fiber are all not able to be used in ECC. But flash ash and PVA fiber are very suit for using in ECC, the toughness of ECC increases with the increase of their content.

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