Nitridation of Ni-based alloys: thermodynamics, kinetics, and deformation phenomena accompanying internal precipitation

R E S U M OO objetivo do presente estudo foi avaliar a influência da precipitação interna sobre a composição e estrutura da regeneração natural em um trecho de floresta ombrófila densa aluvial no estuário amazônico. Os dados foram coletados de fevereiro a julho de 2016, em quatro parcelas de 20 x 20m, subdivididas em subparcelas de 1 x 1m para análise da composição florística e estrutural da regeneração e instalados 11 pluviômetros para amostragem da precipitação. Houve pouca variação na quantidade de indivíduos, famílias, gêneros e espécies entre o período chuvoso e o menos chuvoso. Pariana campestris Aubl., Anthurium sinuatum Benth. ex, Schott, Costus arabicus L. e Costus spicatus (Jacq.) Sw. foram mais representativas devido aos impactos antrópicos na área. Conclui-se que não houve influência da precipitação interna na abundância e na riqueza de espécies da regeneração natural.Palavras-chave: Floresta de várzea; florística; estrutura. A B S T R A C T The objective of the present study was to evaluate the influence of internal precipitation on the composition and structure of natural regeneration in an alluvial dense ombrophilous forest in the Amazonian estuary. The data were collected from february to july 2016, in four 20 x 20m plots, subdivided into 1x1m subplots to analyze the floristic and structural composition of the regeneration and using 11 pluviometers to sample the precipitation. There was little variation in the number of individuals, families, genera and species between the rainy season and the less rainy season. Pariana campestris Aubl., Anthurium sinuatum Benth. Schott, Costus arabicus L. and Costus spicatus (Jacq.) Sw. were more representative due to anthropic impacts on the area. It was concluded that there was no influence of internal precipitation on the abundance and richness of natural regeneration species.Keywords: Floodplain forest, Floristic, Structure.

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STEM/X-ray microanalysis across α/γ interfaces in Fe-Ni meteorites

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100109227 ◽

1978 ◽

Vol 36 (1) ◽

pp. 416-417

Author(s):

D. B. Williams ◽

J. I. Goldstein

Keyword(s):

Electron Beam ◽

Spatial Resolution ◽

Ion Beam ◽

Finite Thickness ◽

Theoretical Models ◽

X Ray ◽

Internal Precipitation ◽

Precipitation Reactions ◽

Two Phases ◽

Characteristic Microstructure

Fe-Ni meteorites have cooled at rates ∼1-10°C/106 years giving rise to a characteristic microstructure of Widmanstatten bcc α plates that have nucleated and grown from the parent fcc γ phase. This transformation results in rejection of Ni into the remaining γ, which also exhibits a variety of internal precipitation reactions. The Ni concentration at the α/γ interface should be close to the equilibrium value between the two phases and this has been determined in several meteorites, using a Philips EM300 TEM/STEM equipped with X-ray microanalytical facilities. The sharp α/γ interface also permits a practical determination to be made of the spatial resolution of the technique. This has been performed and the result compared with the predictions of two theoretical models describing the spatial resolution in terms of the spreading of the electron beam within specimens of finite thickness.Specimens of the meteorites were sectioned such that the α/γ interface was normal to the surface, then 3mm discs were spark machined, ground to ∼100 μm thick, then ion beam thinned to electron transparency

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Diffusion-Controlled Internal Precipitation Reactions

Handbook of Solid State Diffusion, Volume 2 ◽

10.1016/b978-0-12-804548-0.00007-4 ◽

2017 ◽

pp. 277-337

Author(s):

Alexander Kodentsov

Keyword(s):

Internal Precipitation ◽

Diffusion Controlled ◽

Precipitation Reactions

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Predicting Internal Oxidation: Building on the Wagner Model

Materials Science Forum ◽

10.4028/www.scientific.net/msf.696.1 ◽

2011 ◽

Vol 696 ◽

pp. 1-11 ◽

Cited By ~ 8

Author(s):

David J. Young

Keyword(s):

Internal Oxidation ◽

Binary Alloy ◽

Reactive Component ◽

Internal Interface ◽

Parabolic Kinetics ◽

Internal Precipitation ◽

Diffusion Effects ◽

Multiple Oxidants ◽

Low Solubility ◽

Dilute Alloy

Wagner’s 1959 diffusion model of the internal oxidation process provided a method of predicting the rate at which a binary alloy was penetrated by dissolved oxygen as it precipitated the more reactive (but dilute) alloy component. Parabolic kinetics were predicted to depend on oxygen permeability in the unreacted alloy solvent and also, in cases where the reactive component was sufficiently mobile, the diffusion coefficient of the latter. The model has proven very successful, but is restricted to single oxidant-binary alloy systems, in which the precipitated oxide has extremely low solubility. This paper reviews recent results on a number of internal precipitation processes which cannot be described with the Wagner theory. These include formation of low stability carbides and nitrades; internal precipitation driven by multiple oxidants; the templating effects of prior precipitates on subsequently formed corrosion products; cellular precipitation morphologies; internal interface diffusion effects; volume changes in the reaction zone and the effects upon them of simultaneous external scaling.

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Determining forest litter interception in an area of the Cerrado sensu stricto

RBRH ◽

10.1590/2318-0331.231820170146 ◽

2018 ◽

Vol 23 (0) ◽

Author(s):

Lívia Malacarne Pinheiro Rosalem ◽

Jamil Alexandre Ayach Anache ◽

Edson Wendland

Keyword(s):

Water Balance ◽

Empirical Studies ◽

Forest Litter ◽

Sensu Stricto ◽

Total Rainfall ◽

Internal Precipitation ◽

Litter Interception ◽

Litter Quantity

ABSTRACT Mainly due to the difficulty of directly measuring forest litter interception, many empirical studies on water balance in forests have disregarded this component. In order to assess the magnitude of forest litter interception in an area of the Cerrado s.s. , an estimate of the intercepted volume was made based on equations from two forest litter parameters (Cmax and Cmin) obtained from laboratory assays and monitoring the forest litter quantity. The estimates obtained from the litter interception for 2015 and 2016 were compared with the calculated values of evapotranspiration and internal precipitation of the study area. The total volume of litter interception corresponded on average to 13.4% of the internal precipitation and 8.5% of the total rainfall. Regarding the total annual evapotranspiration, the evaporation from the forest litter interception volume corresponded on average to 10.3% (122 mm) of this total. Forest litter interception for areas such as the Cerrado sensu stricto can have a significant impact on the water balance. This shows the need for directly measuring the forest litter interception, providing more accurate determinations of the rainfall partitioning in these forest areas.

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