کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1447153 988636 2011 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Direct characterization of phase transformations and morphologies in moving reaction zones in Al/Ni nanolaminates using dynamic transmission electron microscopy
موضوعات مرتبط
مهندسی و علوم پایه مهندسی مواد سرامیک و کامپوزیت
پیش نمایش صفحه اول مقاله
Direct characterization of phase transformations and morphologies in moving reaction zones in Al/Ni nanolaminates using dynamic transmission electron microscopy
چکیده انگلیسی

Phase transformations and transient morphologies are examined as exothermic formation reactions self-propagate across Al/Ni nanolaminate films. The rapid evolution of these phases and sub-micrometer morphological features requires nanoscale temporal and spatial resolution that is not available with traditional in situ electron microscopy. This work uses dynamic transmission electron microscopy to identify intermetallic products and phase morphologies, as exothermic formation reactions self-propagate in nanolaminate films grown with 3:2, 2:3 and 1:1 Al/Ni atomic ratios. Single-shot diffraction patterns with 15 ns temporal resolution reveal that the NiAl intermetallic forms within ∼15 ns of the reaction front’s arrival in all three types of films and is the only intermetallic phase to form, as the reactions self-propagate and quench very rapidly. Time-resolved imaging reveals a transient cellular morphology in the Al-rich and Ni-rich foils, but not in the equiatomic films. The cellular features in the Al-rich and Ni-rich films are attributed to a cooling trajectory through a two-phase field of liquid + NiAl.


► Fast phase transformations are examined in Al/Ni reactive nanolaminates.
► Results visible only by dynamic transmission electron microscopy at ns resolution.
► NiAl forms under 15 ns after reaction front in all three stoichiometries studied.
► DTEM imaging reveals a transient cellular morphology in nonequiatomic films.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Acta Materialia - Volume 59, Issue 9, May 2011, Pages 3571–3580
نویسندگان
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