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An Experimental Study of Metallic Diffusion and Phase Equilibria in Fremdlinge

Blum, J. D. and Wasserburg, G. J. and Armstrong, J. T. and Hutcheon, I. E. and Beckett, J. R. and Stolper, E. M. (1987) An Experimental Study of Metallic Diffusion and Phase Equilibria in Fremdlinge. Meteoritics, 22 (4). p. 331. ISSN 0026-1114.

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Fremdlinge are opaque assemblages within CAis that are mainly composed of NiFe metal, V-magnetite and µm-sized RuOs nuggets. The prevailing scenario for their origin includes condensation, aggregation and equilibration at low T (≾ 600°C); they are then thought to be introduced into CAis at high T, followed by rapid cooling, thereby preserving the textures and assemblages from the pre-CAl, low T histories (Armstrong et al., 1985; Armstrong et al., 1987). A constraint on cooling rates of Fremdlinge comes from sharp contacts observed between RuOs nuggets and NiFe metals that enclose them. To determine the length of time that these contacts could have been held at high T, thin-film diffusion experiments were conducted with an electroplated Ru film on Ni. Samples were annealed at 1400, 1200, 1000 and 800°C for 0.3-137 hours. Measured Ru profiles in Ni were consistent with the following Arrhenius expression: D(cm^2/sec) = 0.0050exp(-2.3 x 10^(12)/RT) (T in K, R in Cgs units). Based on these data, we calculate that cooling rates of ≳ 10^5C/hr are necessary to preserve sharp contacts between RuOs and NiFe metals if they experienced the T of CAl melting (~ 1400°C) (Stolper and Paque, 1986). We consider this rate unreasonable in light of cooling rates inferred from experimental studies of the silicate portions of CAis (10^(-1) to 10^2°C/hr) (Stolper and Paque, 1986).

Item Type:Article
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URLURL TypeDescription
Wasserburg, G. J.0000-0002-7957-8029
Stolper, E. M.0000-0001-8008-8804
Additional Information:© 1987 Meteoritical Society.
Group:UNSPECIFIED, Division of Geological and Planetary Sciences
Issue or Number:4
Record Number:CaltechAUTHORS:20130313-091753466
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Official Citation:An Experimental Study of Metallic Diffusion and Phase Equilibria in Fremdlinge Blum, J. D.; Wasserburg, G. J.; Armstrong, J. T.; Hutcheon, I. E.; Beckett, J. R.; Stolper, E. M. Meteoritics, Vol. 22, p.331
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37487
Deposited By: Ruth Sustaita
Deposited On:13 Mar 2013 17:14
Last Modified:03 Oct 2019 04:48

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