Interlamellar spacing in discontinuous precipitation

It is currently well established that, for an Al-Ag alloy quenched from the α phase and aged within the metastable solvus, the aging sequence is: supersaturated α → GP zones → γ’ → γ (Ag2Al). While GP zones and plate-shaped γ’ are metastable phases, continuously distributed in the matrix, formation of the equilibrium phase γ takes place at grain boundaries by discontinuous precipitation (DP). The crystal structure of both γ’ and γ is hep with the following orientation relationship with respect to the fee α matrix: {0001}γ′,γ // {111}α, <1120>γ′,γ, // <110>α.The mechanisms and kinetics of continuous matrix precipitation (CMP) in dilute Al-Ag alloys have been studied in considerable detail. The quantitative description of DP kinetics, however, has received less attention. The present contribution reports the microstructural evolution resulting from aging an Al-Ag alloy with Ag content higher than those previously reported in the literature, focusing the observations of γ' plate-shaped metastable precipitates.

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Effect of Interlamellar Spacing on the Constitutive Behavior of Pearlitic Steels Via Damage and Multiscale Analysis

International Journal for Multiscale Computational Engineering ◽

10.1615/intjmultcompeng.v3.i2.40 ◽

2005 ◽

Vol 3 (2) ◽

pp. 161-176

Author(s):

X. Peng ◽

J. Fan ◽

W. Pi

Keyword(s):

Multiscale Analysis ◽

Interlamellar Spacing ◽

Constitutive Behavior

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Application of the Disector to Determine the Distribution of True Interlamellar Spacing in Lamellar Microstructures

Practical Metallography ◽

10.3139/147.110050 ◽

2010 ◽

Vol 47 (4) ◽

pp. 206-216

Author(s):

S. Sankaran ◽

Piyush Pathak ◽

Sandeep Sangal ◽

K.A. Padmanabhan

Keyword(s):

Interlamellar Spacing

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The Interlamellar Spacing of Pearlite

Practical Metallography ◽

10.3139/147.110357 ◽

2015 ◽

Vol 52 (8) ◽

pp. 419-436 ◽

Cited By ~ 5

Author(s):

G. F. Vander Voort

Keyword(s):

Interlamellar Spacing

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The effects of preparation and some physico-chemical parameters on the properties of styrene catalyst - based on iron(III) oxide.

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19830421 ◽

1983 ◽

Vol 48 (2) ◽

pp. 421-438 ◽

Cited By ~ 1

Author(s):

Milan Pospíšil ◽

Jiří Spěváček ◽

Jindřich Kryška

Keyword(s):

Heat Treatment ◽

Discontinuous Precipitation ◽

Microstructural Analysis ◽

Sulfate Solution ◽

Chemical Parameters ◽

Physico Chemical ◽

Additional Thermal Treatment ◽

Genetic Sequences ◽

Dehydrogenation Of Ethylbenzene ◽

Thermal Stability Of

Hydrated iron(III) oxides were obtained by discontinuous precipitation of an iron(II) sulfate solution with aqueous ammonium - saturated with carbon dioxide to different CO2/NH3 ratios. An additional thermal treatment of these oxides, under different conditions, provided genetic sequences of intermediates and their final products - catalysts on a Fe2O3/K2O basis, with different promoters. The catalysts were studied by means of the microstructural; analysis, thermogravimetry, DTA, IR spectroscopy and further tested by the dehydrogenation of ethylbenzene to styrene. It was observed that by changing the CO2/NH3 ratio in the precipitation of the initial solutions one can influence some of the properties, as well as, the morphology and thermal stability of the initial intermediates of the preparation of the catalysts. The above mentioned properties become practically unified with the increasing number of the heat treatment operations, with all the investigated catalysts - with the exception of the catalysts' behaviour during their reduction with hydrogen. The presence of iron oxides in various valency states and the different phase composition of the catalysts during their reduction affect the final activity and selectivity of the catalyst in the reaction under the study.

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