A detailed study of the Al3Ni formation reaction using nanocalorimetry

[Display omitted] •Small-scale, high-rate calorimetry is used to study the Al3Ni formation reaction.•100-nm-thick samples are tested at heating rates between 103K/s and 105K/s.•Isoconversional analysis indicates two reaction stages: interdiffusion and growth.•Growth stage is an excellent fit to Avra...

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Bibliographic Details
Published in:Thermochimica acta 2017-12, Vol.658 (C), p.72-83
Main Authors: Grapes, Michael D., Santala, Melissa K., Campbell, Geoffrey H., LaVan, David A., Weihs, Timothy P.
Format: Article
Language:English
Subjects:
Aluminum
INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Isoconversional analysis
MATERIALS SCIENCE
Nanocalorimetry
NANOSCIENCE AND NANOTECHNOLOGY
Nickel
Reaction mechanisms
Reactive multilayers
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Summary:[Display omitted] •Small-scale, high-rate calorimetry is used to study the Al3Ni formation reaction.•100-nm-thick samples are tested at heating rates between 103K/s and 105K/s.•Isoconversional analysis indicates two reaction stages: interdiffusion and growth.•Growth stage is an excellent fit to Avrami kinetics with exponent 0.5.•Model suggests that Al3Ni nucleates in the grain boundaries and grows laterally. The Al3Ni formation reaction was examined at 11 heating rates ranging from 1000K/s to 100,000K/s using high-rate nanocalorimetry, time-resolved electron microscopy, isoconversional analysis, and combined kinetic analysis. Two main reaction steps are identified. In the first, interdiffusion occurs between reactants without product nucleation. The estimated activation energy for this process, 113kJ/mol±4kJ/mol, suggests grain boundary diffusion as the most likely controlling mechanism. In the second step, the Al3Ni product phase nucleates and grows. Here, the estimated activation energy of 137kJ/mol±4kJ/mol suggests that growth is enabled by diffusion of Ni through bulk Al. Combined kinetic analysis of the growth regime yields an Avrami reaction model with an exponent of 0.5, implying 1D diffusion-limited growth from a fixed number of randomly distributed nuclei. Combining the results for the two regimes, we propose a mechanism where the Al3Ni product initially nucleates along the grain boundaries and then grows laterally until the reactants are consumed.
ISSN:0040-6031
1872-762X
DOI:10.1016/j.tca.2017.10.018