Deducing growth mechanisms for minerals from the shapes of crystal size distributions

Eberl, Dennis D.; Drits, Victor A.; Środoń, Jan

doi:10.2475/ajs.298.6.499

Cited by 217 publications

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“…These events can influence only some inclusions in the outer layer of cluster but not inclusions in the inner part of the cluster. Thus, the only growth mechanism for inner cluster inclusions is Ostwald ripening, which tends to preserve original nucleation-derived lognormal PDF 18,19) as shown in Fig. 5.…”

Section: Existence Of Liquid Ti-al-o Oxide Inclusionsmentioning

confidence: 99%

“…A lognormal shape PDF appears whenever evidences indicated the occurrence of active nucleation (deoxidation or reoxidation) in the present study, which is supported by the modeling of nucleation and growth kinetics. 7,8,[18][19][20] This situation is characterized by net mass transfer between solute and inclusion. Inclusion PDF show a power-law distribution that is linear on the logarithm PDF plots when there is no deoxidation or reoxidation event for a while in the secondary steelmaking, which is expected for the processes where particle breakup/coalescence control the size distribution (e.g.…”

Section: Summary Of Changes In Inclusion Pdf From Secondary Steelmakimentioning

confidence: 99%

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Inclusion Population Evolution in Ti-alloyed Al-killed Steel during Secondary Steelmaking Process

et al. 2012

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This paper presents a new approach towards the evolution of non-metallic inclusion (NMI) populations in Ti-alloyed Al-killed steels, based on an extensive inclusion analysis campaign at Tata Steel Europe, IJmuiden Works. Automated SEM techniques were used to characterize the inclusion populations in 120 steel samples taken from nine heats out of two casting series of this steel grade. As NMI in Ti-alloyed Alkilled steels are overwhelmingly dominated by chemically simple Al2O3, most of the process relevant information lies in the analysis of particle size distribution during the secondary steelmaking process. The population density function (PDF) concept was applied, for the first time, to the characterization of inclusion size distributions sampled from secondary steelmaking practice. Two size distribution forms predominate in the entire dataset: i) Lognormal size distributions associated with active nucleation and growth of alumina (deoxidation and reoxidation), indicating net transfer of matter between NMI and solutes in liquid steel and ii) Power-law size distributions, associated with an inclusion population in chemical equilibrium with the melt and subject to collision/breakup processes controlling the distributions. Based on inclusion PDF observations, it is found that the size distribution of alumina inclusions suspended in steel melt, after equilibration and effective float out of large inclusions, tends to approach a Reference Distribution of powerlaw type function (f(r) = a ⋅ r -3.5 ) that appears to be a fundamental feature of the alumina-steel system. This Reference Distribution can guide efforts to improve and engineer inclusion populations for a better controlled steel product.KEY WORDS: non-metallic inclusion; inclusion population density function; inclusion size distribution; secondary steelmaking.

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Section: Existence Of Liquid Ti-al-o Oxide Inclusionsmentioning

confidence: 99%

Section: Summary Of Changes In Inclusion Pdf From Secondary Steelmakimentioning

confidence: 99%

Inclusion Population Evolution in Ti-alloyed Al-killed Steel during Secondary Steelmaking Process

et al. 2012

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“…calculates shapes for crystal size distributions (CSDs) formed by theoretical crystal growth mechanisms described in Eberl, Drits, and Írodo~, 1998. Assuming that the theory is correct, 7 crystal growth mechanisms can be determined by comparing GALOPER calculated CSDs to those measured for natural samples.…”

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confidence: 99%

User's Guide to Galoper: A Program for Simulating the Shapes of Crystal Size Distributions from Growth Mechanisms - and Associated Programs

Eberl¹,

Drits²,

Środoń³

2000

Open-File Report

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“…Whereas the size distributions of inorganic magnetite and BIM magnetite are typically lognormal (i.e. the logarithms of the particle sizes have a normal [Gaussian] distribution), the shapes of the magnetosome size distributions are asymmetric, with a sharp high-end cutoff comparable to distributions produced by Ostwald ripening [47].…”

Section: Terrestrial Biogenic Magnetitementioning

confidence: 99%

Magnetite biomineralization and ancient life on Mars

Frankel

Buseck

2000

Current Opinion in Chemical Biology

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Certain chemical and mineral features of the Martian meteorite ALH84001 were reported in 1996 to be probable evidence of ancient life on Mars. In spite of new observations and interpretations, the question of ancient life on Mars remains unresolved. Putative biogenic, nanometer magnetite has now become a leading focus in the debate. . Similarly, possible sample-preparation artifacts [11,12], terrestrial weathering, and similarity to mineral features produced in crystal-growth experiments and in lunar meteorites [13°,14°] make the BSOs unconvincing biomarkers. We believe that although sufficient evidence has not been found to exclude a Martian biogenic origin for all the PAHs and BSOs, these features do not provide compelling evidence for the ancient life hypothesis. Carbonate globulesThe age of the carbonates shows that they originated onMars. In the original hypothesis, McKay et al. [4] proposed that the carbonate globules precipitated from aqueous solutions that infiltrated fractures in the ALH84001 matrix, with subsequent deposition of the carbonate minerals modulated by microorganisms. There has been considerable debate about the origin of these carbonates, however, and evidence for both high-temperature and low-temperature formation has been presented [15,16°-18°,19-22]. As chemical zoning could also result from non biological deposition from aqueous solution, zoning may not be a reliable indicator of biological activity. Complications can also arise from the possible effects of subsequent impacts, including shock melting of the carbonates [1 r,23,24]. On the other hand, it has been argued that the chemical zoning and oxygen isotope non-equilibrium are evidence against prolonged heating of the carbonates [21].Nanometer magnetite crystals isolated from ALH84001 carbonates with whisker (1), quasi-rectangular (2), and irregular projected shapes (KL Thomas-Keptra, personal communication). Nanometer iron sulfides in carbonate globules Nanometer magnetite from terrestrial sourcesNanometer magnetite occurs in lava flows but usually con tains substantial amounts of titanium. It has also been recovered from soils and sediments [38,39], including deep sea sediments. Some of these crystals were identified as biogenic on the basis of their shape and size similarity to known biogenic magnetite in magnetotactic bacteria. In some cases, a biogenic origin was supported by the organi zation of the magnetite crystals in chains. However, authigenic (nonbiological) nanometer magnetite can also be produced in sediments [38]. The process of magnetite deposition within the magnetosome membrane is not well understood, although it is thought that the membrane controls nucleation and growth of the crystals. Fe(III) is taken up by cells via an oxygen-dependent transport system, deposited in the membrane, and rapidly converted to magnetite [44]. Elongated magnetosome habits in some species could result from an anisotropic flux of ions through the mem brane, or from anisotropic interactions of the membrane with the growing crystal. ...

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Deducing growth mechanisms for minerals from the shapes of crystal size distributions

Cited by 217 publications

References 0 publications

Inclusion Population Evolution in Ti-alloyed Al-killed Steel during Secondary Steelmaking Process

Inclusion Population Evolution in Ti-alloyed Al-killed Steel during Secondary Steelmaking Process

User's Guide to Galoper: A Program for Simulating the Shapes of Crystal Size Distributions from Growth Mechanisms - and Associated Programs

Magnetite biomineralization and ancient life on Mars

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