Effects of Co on the Solidification and Precipitation Behaviors of IN 718 Alloy

2015 ◽  
Vol 816 ◽  
pp. 613-619 ◽  
Author(s):  
Xin Xin ◽  
Wei Hong Zhang ◽  
Lian Xu Yu ◽  
Fang Liu ◽  
Dan Jia ◽  
...  
Keyword(s):  
Interdendritic Region ◽  
Mass Fraction ◽  
Volume Fraction ◽  
Laves Phase ◽  
Solidification Point ◽  
Dendrite Core ◽  
Residual Liquid ◽  
Gray Phase ◽  
Co Alloys

The effects of Co from 0 to 11.60 % (in mass fraction) on the solidification and precipitation behaviors of IN 718 alloy had been investigated. The results showed that the volume fraction of the dendrite core increased with the addition of Co. In the alloys with 0-5.84 %Co, the addition of Co could restrain the precipitation of blocky Laves phase and promoted the formation of eutectic Laves phase. In the alloys with 9.00-11.60 % Co, the eutectic gray phase and small blocky Laves phase precipitated in the interdendritic region. The eutectic gray phase increased and small blocky Laves phase decreased with increasing Co. The parallel lath-like δ-Ni3Nb phase was observed to precipitate in some interdendritic region without the formation of gray phase and Laves phase in the 9.00-11.60 % Co alloys. Further research found that Co slightly segregated in the dendrite core and markedly raised the solubility of element Mo in the dendrite core which resulted in reduced Mo in the residual liquid, and consequently, restrained Laves phase while promoted the precipitation of Mo-depleted gray phase and δ-Ni3Nb phase. Furthermore, Co was seemed to elevate the solidification point of the γ matrix while decrease that of the Laves phase.

Effect of Hot Isostatic Pressing on the Microstructure of K417G Cast Turbine Discs

2015 ◽  
Vol 816 ◽  
pp. 557-561 ◽  
Author(s):  
Jie Li ◽  
Chao Yuan ◽  
Jian Ting Guo ◽  
Jie Shan Hou ◽  
Lan Zhang Zhou
Keyword(s):  
Interdendritic Region ◽  
Volume Fraction ◽  
Hot Isostatic Pressing ◽  
Dendritic Structure ◽  
Experimental Results ◽  
Dendrite Core ◽  
Slow Cooling ◽  
Isostatic Pressing

The present study focused on the effect of hot isostatic pressing (HIP) treatment on the microstructure of K417G superalloy. The experimental results showed that after the HIP treatment the size and volume fraction of the porosities significantly decreased. In addition, the dendritic structure and γ/γ' eutectics in the as-cast specimens became obscure after the HIP treatment due to the improvement of segregation. The γ′ phases in the dendrite core were smaller than those in the interdendritic region, whether in the as-cast or HIP specimens. The slow cooling at the end of the HIP treatment leads to the irregular morphology of the γ′ phases.

Engine performance and emission characteristics of a compression ignition engine fuelled with diesel/dimethoxymethane blends

2005 ◽  
Vol 219 (7) ◽  
pp. 905-914 ◽  
Author(s):  
Y Ren ◽  
Z H Huang ◽  
D M Jiang ◽  
L X Liu ◽  
K Zeng ◽  
...  
Keyword(s):  
Thermal Efficiency ◽  
Mass Fraction ◽  
Volume Fraction ◽  
Engine Performance ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Performance And Emission ◽  
Fuel Blends ◽  
Performance And Emissions ◽  
Combustion Phase

The performance and emissions of a compression ignition engine fuelled with diesel/dimethoxymethane (DMM) blends were studied. The results showed that the engine's thermal efficiency increased and the diesel equivalent brake specific fuel consumption (b.s.f.c.) decreased as the oxygen mass fraction (or DMM mass fraction) of the diesel/DMM blends increased. This change in the diesel/DMM blends was caused by an increased fraction of the premixed combustion phase, an oxygen enrichment, and an improvement in the diffusive combustion phase. A remarkable reduction in the exhaust CO and smoke can be achieved when operating on the diesel/DMM blend. Flat NO x/smoke and thermal efficiency/smoke curves are presented when operating on the diesel/DMM fuel blends, and a simultaneous reduction in both NO x and smoke can be realized at large DMM addition. Thermal efficiency and NO x give the highest value at 2 per cent oxygen mass fraction (or 5 per cent DMM volume fraction) for the combustion of diesel/DMM blends.

scholarly journals The Dilatometric Analysis of the High Carbon Alloys from Ni-Ta-Al-M System

2014 ◽  
Vol 59 (3) ◽  
pp. 977-980 ◽  
Author(s):  
P. Bała
Keyword(s):  
Elevated Temperatures ◽  
Volume Fraction ◽  
Intermetallic Phase ◽  
Coarse Grained ◽  
Precipitation Process ◽  
Cast State ◽  
High Carbon ◽  
Chromium Carbides ◽  
Tantalum Carbides ◽  
Co Alloys

Abstract In the following work presents results of high carbon alloys from the Ni-Ta-Al-M system are presented. The alloys have been designed to have a good tribological properties at elevated temperatures. Despite availability of numerous hot work tool materials there is still a growing need for new alloys showing unique properties, which could be used under heavy duty conditions, i.e. at high temperatures, in a chemically aggressive environment and under heavy wear conditions. A characteristic, coarse-grained dendritic microstructure occurs in the investigated alloys in the as-cast condition. Primary dendrites with secondary branches can be observed. Tantalum carbides of MC type and graphite precipitations are distributed in interdendritic spaces in the Ni-Ta-Al-C and Ni-Ta-Al-C-Co alloys, while Tantalum carbides of MC type and Chromium carbides of M7C3 type appeared in the Ni-Ta-Al-C-Co-Cr and Ni-Ta-Al-C-Cr alloys. In all alloys g’ phase is present, however, its volume fraction in the Ni-Ta-Al-C and Ni-Ta-Al-C-Co alloys is small.During heating from as-cast state in Ni-Ta-Al-C and Ni-Ta-Al-C-Co alloys, the beginning of the tantalum carbides precipitation process (MC type) followed (or simultaneous) by the intermetallic phase precipitation (g’ – Ni3(AlTa)) was stated, while in Ni-Ta-Al-C-Co-Cr and Ni-Ta-Al-C-Cr alloys, besides Tantalum carbides also the Chromium carbides precipitation occurred. It means that the investigated alloys were partially supersaturated in as-cast state. Above 1050°C in all investigated alloys the g’ phase is dissolving. In addition, the precipitation of secondary carbides during slow cooling was occured.

scholarly journals Impact of Tungsten on Thermomechanically Induced Precipitation of Laves Phase in High Performance Ferritic (HiperFer) Stainless Steels

2020 ◽  
Vol 10 (13) ◽  
pp. 4472 ◽  
Author(s):  
Jana Pöpperlová ◽  
Xiuru Fan ◽  
Bernd Kuhn ◽  
Wolfgang Bleck ◽  
Ulrich Krupp
Keyword(s):  
Particle Size ◽  
Stainless Steels ◽  
Power Plants ◽  
Volume Fraction ◽  
Laves Phase ◽  
Particle Analysis ◽  
Strengthening Effect ◽  
Tungsten Content ◽  
High Chromium ◽  
The Impact

High-chromium ferritic stainless steels strengthened by Laves phase precipitates were developed for a high-temperature application in steam power plants. The impact of tungsten content on the precipitation of the intermetallic Laves phase during the newly developed thermomechanical process route was investigated. Due to rapid thermomechanically induced precipitation, a considerable reduction in processing time in comparison to the conventional solely thermal two-step processing of high chromium ferritic steels was achieved. Nevertheless, comparable mechanical properties at room temperature, i.e., the ultimate tensile strength of 712 MPa and the yield strength of 434 MPa, were obtained. The microstructure was analyzed by scanning electron microscopy (SEM) in combination with digital particle analysis, to estimate the particle size and the phase fraction of the Laves phase. The mean particle size of 52 nm and the volume fraction of 4.11% were achieved. Due to the tungsten content, an increase in the volume fraction and particle size was observed, giving rise to the higher strengthening effect.

scholarly journals Loss coefficients of ice slurry in sudden pipe contractions

2010 ◽  
Vol 31 (3) ◽  
pp. 73-86
Author(s):  
Łukasz Mika
Keyword(s):  
Mass Fraction ◽  
Flow Resistance ◽  
Volume Fraction ◽  
Experimental Studies ◽  
Solid Particles ◽  
Minimal Flow ◽  
Ice Slurry ◽  
Slurry Flow ◽  
Flow Through ◽  
Loss Coefficients

Loss coefficients of ice slurry in sudden pipe contractionsIn this paper, flow systems which are commonly used in fittings elements such as contractions in ice slurry pipelines, are experimentally investigated. In the study reported in this paper, the consideration was given to the specific features of the ice slurry flow in which the flow behaviour depends mainly on the volume fraction of solid particles. The results of the experimental studies on the flow resistance, presented herein, enabled to determine the loss coefficient during the ice slurry flow through the sudden pipe contraction. The mass fraction of solid particles in the slurry ranged from 5 to 30%. The experimental studies were conducted on a few variants of the most common contractions of copper pipes: 28/22 mm, 28/18 mm, 28/15 mm, 22/18 mm, 22/15 mm and 18/15 mm. The recommended (with respect to minimal flow resistance) range of the Reynolds number (Re about 3000-4000) for the ice slurry flow through sudden contractions was presented in this paper.

scholarly journals Soot Volume Fraction Profiles in Forced-Combusting Boundary Layers

1983 ◽  
Vol 105 (1) ◽  
pp. 159-165 ◽  
Author(s):  
R. A. Beier ◽  
P. J. Pagni
Keyword(s):  
Boundary Layer ◽  
Mass Fraction ◽  
Volume Fraction ◽  
Diffusion Flames ◽  
Soot Volume Fraction ◽  
Liquid Hydrocarbon ◽  
Forced Flow ◽  
Volume Fractions ◽  
Ambient Oxygen ◽  
Mass Fractions

A multiwavelength laser transmission technique is used to determine soot volume fraction fields and aproximate particle size distributions in a forced flow combusting boundary layer. Measurements are made in diffusion flames of polymethylmethacrylate (PMMA) and five liquid hydrocarbon fuels (n-heptane, iso-octane, cyclohexane, cyclohexene, and toluene) with ambient oxygen mass fractions in the range of 0.23 ≲ Y0∞ ≲ 0.50. Soot is observed in a region between the pyrolyzing fuel surface and the flame zone. Soot volume fraction increases monotonically with Y0∞, e.g., n-heptane and PMMA are similar with soot volume fractions, fν, ranging from fν ∼ 5 × 10−7 at Y0∞ = 0.23 to fν ∼ 5 × 10−6 at Y0∞ = 0.50. For an oxygen mass fraction the same as air, Y0∞ = 0.23, soot volume fractions are approximately the same as values previously reported in pool fires and a free combusting boundary layer. However, the shape of the fν profile changes with more soot near the flame in forced flow than in free flow due to the different y-velocity fields in these two systems. For all fuels tested, a most probable particle radius is between 20 nm and 80 nm, and does not appear to change substantially with location, fuel, or oxygen mass fraction.

Effect of CuO Nanoparticle Concentration on R134a/Lubricant Pool-Boiling Heat Transfer

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
M. A. Kedzierski
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Mass Fraction ◽  
Flat Surface ◽  
Volume Fraction ◽  
Nanoparticle Concentration ◽  
Transfer Enhancement ◽  
Fundamental Understanding ◽  
Determining Factor ◽  
Cuo Nanoparticle

This paper quantifies the influence of copper (II) oxide (CuO) nanoparticle concentration on the boiling performance of R134a/polyolester mixtures on a roughened horizontal flat surface. Nanofluids are liquids that contain dispersed nanosize particles. Two lubricant-based nanofluids (nanolubricants) were made with a synthetic polyolester and 30 nm diameter CuO particles to 1% and 0.5% volume fractions, respectively. As reported in a previous study for the 1% volume fraction nanolubricant, a 0.5% nanolubricant mass fraction with R134a resulted in a heat transfer enhancement relative to the heat transfer of pure R134a/polyolester (99.5/0.5) between 50% and 275%. The same study had shown that increasing the mass fraction of the 1% volume fraction nanolubricant resulted in smaller, but significant, boiling heat transfer enhancements. The present study shows that the use of a nanolubricant with half the concentration of CuO nanoparticles (0.5% by volume) resulted in either no improvement or boiling heat transfer degradations with respect to the R134a/polyolester mixtures without nanoparticles. Consequently, significant refrigerant/lubricant boiling heat transfer enhancements are possible with nanoparticles; however, the nanoparticle concentration is an important determining factor. Further research with nanolubricants and refrigerants is required to establish a fundamental understanding of the mechanisms that control nanofluid heat transfer.

Effect of Hot Isostatic Pressing on the Microstructure of Single Crystal Ni-Based Superalloy DD10

2013 ◽  
Vol 747-748 ◽  
pp. 772-776
Author(s):  
Li Jun Liu ◽  
Ming Xue ◽  
Jing Yang Chen ◽  
La Mei Cao
Keyword(s):  
Electron Microscope ◽  
Single Crystal ◽  
Interdendritic Region ◽  
Hot Isostatic Pressing ◽  
Optical Microscope ◽  
Dendrite Core ◽  
Dendritic Segregation ◽  
Third Generation ◽  
Isostatic Pressing ◽  
Scanning Electron

The effects of hot isostatic pressing on the microstructures of a third generation single crystal Ni-based superalloy DD10 were investigated by using optical microscope (OM), scanning electron microscope (SEM), electron microprobe analyzer (EPMA). The results showed that the micropores in the interdendritic region were eliminated completely after hot isostatic pressing at 1320 and 150MPa. Meanwhile, the morphology of γ precipitates changed to be more cuboidal and the distribution of γ precipitates in both dendrite core and interdendritic region became more uniform after hot isostatic pressing. Hot isostatic pressing also promoted the homogenization of the composition between dendrite core and interdendritic region and the dendritic segregation of Re, W, Al and Ta was decreased.

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