Interdiffusion and Intrinsic Diffusion in the Mg-Al System
Abstract
Solid-to-solid diffusion couples were assembled and annealed to examine the diffusion between pure Mg (99.96%) and Al (99.999%). Diffusion anneals were carried out at 300 , 350 , and 400 C for 720, 360, and 240 hours, respectively. Optical and scanning electron microscopes were utilized to identify the formation of the intermetallic phases, -Al12Mg17 and -Al3Mg2 and absence of the -phase in the diffusion couples. Thicknesses of the -Al12Mg17 and -Al3Mg2 phases were measured and the parabolic growth constants were calculated to determine the activation energies for the growth, 165 and 86 KJ/mole, respectively. Concentration profiles were determined with electron microprobe analysis using pure elemental standards. Composition-dependent interdiffusion coefficients in Mg-solid solution, -Al12Mg17 and - Al3Mg2 and Al-solid solutions were calculated based on the Boltzmann-Matano analysis. Average effective interdiffusion coefficients for each phase were also calculated, and the magnitude was the highest for the -Al3Mg2 phase, followed by -Al12Mg17, Al-solid solution and Mg-solid solution. Intrinsic diffusion coefficients based on Huemann s analysis (e.g., marker plane) were determined for the ~38 at.% Mg in the -Al3Mg2 phase. Activation energies and the pre-exponential factors for the inter- and intrinsic diffusion coefficients were calculated for the temperature range examined. The -Al3Mg2 phase wasmore »
- Authors:
-
- University of Central Florida
- ORNL
- Publication Date:
- Research Org.:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Org.:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE)
- OSTI Identifier:
- 1054995
- DOE Contract Number:
- DE-AC05-00OR22725
- Resource Type:
- Journal Article
- Journal Name:
- Metallurgical and Materials Transactions A
- Additional Journal Information:
- Journal Volume: 43; Journal Issue: 11; Journal ID: ISSN 1073--5623
- Country of Publication:
- United States
- Language:
- English
- Subject:
- Magnesium; zin; diffusion; interdiffusion; Boltzmann-Matano
Citation Formats
Brennan, Sarah, Bermudez, Katrina, Sohn, Yong Ho, and Kulkarni, Nagraj S. Interdiffusion and Intrinsic Diffusion in the Mg-Al System. United States: N. p., 2012.
Web. doi:10.1007/s11661-012-1248-8.
Brennan, Sarah, Bermudez, Katrina, Sohn, Yong Ho, & Kulkarni, Nagraj S. Interdiffusion and Intrinsic Diffusion in the Mg-Al System. United States. https://doi.org/10.1007/s11661-012-1248-8
Brennan, Sarah, Bermudez, Katrina, Sohn, Yong Ho, and Kulkarni, Nagraj S. 2012.
"Interdiffusion and Intrinsic Diffusion in the Mg-Al System". United States. https://doi.org/10.1007/s11661-012-1248-8.
@article{osti_1054995,
title = {Interdiffusion and Intrinsic Diffusion in the Mg-Al System},
author = {Brennan, Sarah and Bermudez, Katrina and Sohn, Yong Ho and Kulkarni, Nagraj S},
abstractNote = {Solid-to-solid diffusion couples were assembled and annealed to examine the diffusion between pure Mg (99.96%) and Al (99.999%). Diffusion anneals were carried out at 300 , 350 , and 400 C for 720, 360, and 240 hours, respectively. Optical and scanning electron microscopes were utilized to identify the formation of the intermetallic phases, -Al12Mg17 and -Al3Mg2 and absence of the -phase in the diffusion couples. Thicknesses of the -Al12Mg17 and -Al3Mg2 phases were measured and the parabolic growth constants were calculated to determine the activation energies for the growth, 165 and 86 KJ/mole, respectively. Concentration profiles were determined with electron microprobe analysis using pure elemental standards. Composition-dependent interdiffusion coefficients in Mg-solid solution, -Al12Mg17 and - Al3Mg2 and Al-solid solutions were calculated based on the Boltzmann-Matano analysis. Average effective interdiffusion coefficients for each phase were also calculated, and the magnitude was the highest for the -Al3Mg2 phase, followed by -Al12Mg17, Al-solid solution and Mg-solid solution. Intrinsic diffusion coefficients based on Huemann s analysis (e.g., marker plane) were determined for the ~38 at.% Mg in the -Al3Mg2 phase. Activation energies and the pre-exponential factors for the inter- and intrinsic diffusion coefficients were calculated for the temperature range examined. The -Al3Mg2 phase was found to have the lowest activation energies for growth and interdiffusion among all four phases studied. At the marker location in the -Al3Mg2 phase, the intrinsic diffusion of Al was found to be faster than that of Mg. Extrapolations of the impurity diffusion coefficients in the terminal solid solutions were made and compared to the available self- and impurity diffusion data from literature. Thermodynamic factor, tracer diffusion coefficients and atomic mobilities at the marker plane composition were approximated using available literature values of Mg activity in the -Al3Mg2 phase.},
doi = {10.1007/s11661-012-1248-8},
url = {https://www.osti.gov/biblio/1054995},
journal = {Metallurgical and Materials Transactions A},
issn = {1073--5623},
number = 11,
volume = 43,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2012},
month = {Sun Jan 01 00:00:00 EST 2012}
}