Aluminum Impurity Diffusion in Magnesium

Brennan, Sarah; Warren, Andrew P.; Coffey, Kevin R.; Kulkarni, Nagraj; Todd, Peter J.; Kilmov, Mikhail; Sohn, Yong Ho

doi:10.1007/s11669-012-0007-2

Cited by 44 publications

(46 citation statements)

References 9 publications

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“…Furthermore, the SIMS dynamic range for accurate tracer concentration beyond the background concentration spans at most one or two orders of magnitude, which can be insufficient for a reliable fit on a log versus x 2 plot. Additionally, it is necessary to know the background tracer concentration, c b,i , to use Eq 10, unless the tracer is an impurity, in which case Eq 12 can be used (e.g., Al impurity diffusion in Mg [42] ). The background tracer concentration is usually determined by measuring the tracer concentration deep in the bulk of the sample near the asymptotic limit of the depth profile, where instrument noise becomes more significant.…”

Section: Thin-film Solutionmentioning

confidence: 99%

“…Most of the available tracer diffusion data in the Mg alloy system is selfdiffusion data, i.e., diffusion of Mg in pure Mg, and includes both single and polycrystalline data. There are considerable data on impurity diffusion of various elements in pure Mg [39] that have been obtained using both the radiotracer [40,41] and SIMS techniques, [42] as well as firstprinciples methods. [43] The available Mg self-diffusion data have been obtained using the radiotracer technique, which has provided Mg tracer diffusion data at high temperatures (>450-650°C) in polycrystals [44] and single crystals.…”

Section: Introductionmentioning

confidence: 99%

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Overview of SIMS-Based Experimental Studies of Tracer Diffusion in Solids and Application to Mg Self-Diffusion

Kulkarni

Warmack

Radhakrishnan

et al. 2014

J. Phase Equilib. Diffus.

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Tracer diffusivities provide the most fundamental information on diffusion in materials, and are the foundation of robust diffusion databases that enable the use of the Onsager phenomenological formalism with no major assumptions. Compared to traditional radiotracer techniques that utilize radioactive isotopes, the secondary ion mass spectrometry (SIMS)-based thin-film technique for tracer diffusion is based on the use of enriched stable isotopes that can be accurately profiled using SIMS. An overview of the thin-film method for tracer diffusion studies using stable isotopes is provided. Experimental procedures and techniques for the measurement of tracer diffusion coefficients are presented for pure magnesium, which presents some unique challenges due to the ease of oxidation. The development of a modified Shewmon-Rhines diffusion capsule for annealing Mg and an ultra-high vacuum system for sputter deposition of Mg isotopes are discussed. Optimized conditions for accurate SIMS depth profiling in polycrystalline Mg are provided. An automated procedure for correction of heat-up and cool-down times during tracer diffusion annealing is discussed. The non-linear fitting of a SIMS depth profile data using the thin-film Gaussian solution to obtain the tracer diffusivity along with the background tracer concentration and tracer film thickness is demonstrated. An Arrhenius fit of the Mg self-diffusion data obtained using the low-temperature SIMS measurements from this study and the high-temperature radiotracer measurements of Shewmon and Rhines (Trans. AIME 250:1021-1025, 1954) was found to be a good representation of both types of diffusion data over a broad range of temperatures between 250 and 627°C (523 and 900 K).

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Section: Thin-film Solutionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Overview of SIMS-Based Experimental Studies of Tracer Diffusion in Solids and Application to Mg Self-Diffusion

Kulkarni

Warmack

Radhakrishnan

et al. 2014

J. Phase Equilib. Diffus.

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“…The anisotropy of the Al diffusivity became smaller with increasing temperature. While Brennan et al 13 experimentally determined the activation energy and pre-exponential factor of Al impurity diffusion in Mg at a temperature range of 573 K-673 K, they calculated the diffusion coefficient which included contribution from grain boundary diffusion and sputter roughening. Minamino et al 14 investigated an inter-diffusion in the Al-4.06at% Mg alloy under high pressure in a temperature range of 690 -877 K. The diffusion coefficients decreased with pressure, and the activation volume of the inter-diffusion was between 0.81V 0 and 0.87V 0 .…”

Section: Introductionmentioning

confidence: 99%

A study on atomic diffusion behaviours in an Al-Mg compound casting process

2015

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Al and Mg alloys are main lightweight alloys of research interest and they both have superb material properties, i.e., low density and high specific strength, etc. Being different from Al alloys, the corrosion of Mg alloys is much more difficult to control. Therefore to combine merits of these two lightweight alloys as a composite-like structure is an ideal solution through using Al alloys as a protective layer for Mg alloys. Compound casting is a realistic technique to manufacture such a bi-metal structure. In this study, a compound casting technique is employed to fabricate bi-layered samples using Al and Mg and then the samples are analysed using electron probe micro-analyzer (EPMA) to determine diffusion behaviours between Al and Mg. The diffusion mechanism and behaviours between Al and Mg are studied numerically at atomic scale using molecular dynamics (MD) and parametric studies are conducted to find out influences of ambient temperature and pressure on the diffusion behaviours between Al and Mg. The results obtained clearly show the effectiveness of the compound casting process to increase the diffusion between Al and Mg and thus create the Al-base protection layer for Mg. C 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License. [http://dx

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“…The revised Al impurity diffusion coefficients, depending on the orientation of hcp Mg, were plotted in Figure 7(b) and compared with previous studies. [4,7,9] The revised optimized mobilities of Al in hcp Mg along the a-and c-axis of Mg crystal are [5] The present activation energies of the diffusion of Al in hcp Mg along the a-and c-axis are 154.48 ± 3.86 kJ/ mol and 159.48 ± 2.45 kJ/mol, respectively. [5,8] Fig.…”

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confidence: 99%

“…7-Variation of Al impurity diffusion coefficients in hcp Mg along its a-and c-axis directions with temperature. (a) Present results from single crystal diffusion experiment (model and analytical represent the calculations by multiphase diffusion simulation and analytical method, respectively), and (b) comparison with the previous data derived from polycrystalline samples [4,7] and the first principles calculations. [9] …”

mentioning

confidence: 99%