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Title: Rapid Laser Induced Crystallization of Amorphous NiTi Films Observed by Nanosecond Dynamic Transmission Electron Microscopy (DTEM)

Abstract

The crystallization processes of the as-deposited, amorphous NiTi thin films have been studied in detail using techniques such as differential scanning calorimetry and, in-situ TEM. The kinetic data have been analyzed in terms of Johnson-Mehl-Avrami-Kolomogrov (JMAK) semi-empirical formula. The kinetic parameters determined from this analysis have been useful in defining process control parameters for tailoring microstructural features and shape memory properties. Due to the commercial push to shrink thin film-based devices, unique processing techniques have been developed using laser-based annealing to spatially control the microstructure evolution down to sub-micron levels. Nanosecond, pulse laser annealing is particularly attractive since it limits the amount of peripheral heating and unwanted microstructural changes to underlying or surrounding material. However, crystallization under pulsed laser irradiation can differ significantly from conventional thermal annealing, e.g., slow heating in a furnace. This is especially true for amorphous NiTi materials and relevant for shape memory thin film based microelectromechanical systems (MEMS) applications. There is little to no data on the crystallization kinetics of NiTi under pulsed laser irradiation, primarily due to the high crystallization rates intrinsic to high temperature annealing and the spatial and temporal resolution limits of standard techniques. However, with the high time and spatial resolution capabilitiesmore » of the dynamic transmission electron microscope (DTEM) constructed at Lawrence Livermore National Laboratory, the rapid nucleation events occurring from pulsed laser irradiation can be directly observed and nucleation rates can be quantified. This paper briefly explains the DTEM approach and how it used to investigate the pulsed laser induced crystallization processes in NiTi and to determine kinetic parameters.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
983387
Report Number(s):
LLNL-PROC-424900
TRN: US201014%%308
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: Presented at: Shape Memory and Superelastic Technologies, Pacific Grove, CA, United States, May 17 - May 20, 2010
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANNEALING; CALORIMETRY; CRYSTALLIZATION; ELECTRON MICROSCOPES; HEATING; IRRADIATION; KINETICS; LASERS; LAWRENCE LIVERMORE NATIONAL LABORATORY; MICROSTRUCTURE; NUCLEATION; PROCESS CONTROL; PROCESSING; RESOLUTION; SHAPE; SPATIAL RESOLUTION; THIN FILMS; TRANSMISSION ELECTRON MICROSCOPY

Citation Formats

LaGrange, T, Campbell, G H, Browning, N D, Reed, B W, and Grummon, D S. Rapid Laser Induced Crystallization of Amorphous NiTi Films Observed by Nanosecond Dynamic Transmission Electron Microscopy (DTEM). United States: N. p., 2010. Web.
LaGrange, T, Campbell, G H, Browning, N D, Reed, B W, & Grummon, D S. Rapid Laser Induced Crystallization of Amorphous NiTi Films Observed by Nanosecond Dynamic Transmission Electron Microscopy (DTEM). United States.
LaGrange, T, Campbell, G H, Browning, N D, Reed, B W, and Grummon, D S. 2010. "Rapid Laser Induced Crystallization of Amorphous NiTi Films Observed by Nanosecond Dynamic Transmission Electron Microscopy (DTEM)". United States. https://www.osti.gov/servlets/purl/983387.
@article{osti_983387,
title = {Rapid Laser Induced Crystallization of Amorphous NiTi Films Observed by Nanosecond Dynamic Transmission Electron Microscopy (DTEM)},
author = {LaGrange, T and Campbell, G H and Browning, N D and Reed, B W and Grummon, D S},
abstractNote = {The crystallization processes of the as-deposited, amorphous NiTi thin films have been studied in detail using techniques such as differential scanning calorimetry and, in-situ TEM. The kinetic data have been analyzed in terms of Johnson-Mehl-Avrami-Kolomogrov (JMAK) semi-empirical formula. The kinetic parameters determined from this analysis have been useful in defining process control parameters for tailoring microstructural features and shape memory properties. Due to the commercial push to shrink thin film-based devices, unique processing techniques have been developed using laser-based annealing to spatially control the microstructure evolution down to sub-micron levels. Nanosecond, pulse laser annealing is particularly attractive since it limits the amount of peripheral heating and unwanted microstructural changes to underlying or surrounding material. However, crystallization under pulsed laser irradiation can differ significantly from conventional thermal annealing, e.g., slow heating in a furnace. This is especially true for amorphous NiTi materials and relevant for shape memory thin film based microelectromechanical systems (MEMS) applications. There is little to no data on the crystallization kinetics of NiTi under pulsed laser irradiation, primarily due to the high crystallization rates intrinsic to high temperature annealing and the spatial and temporal resolution limits of standard techniques. However, with the high time and spatial resolution capabilities of the dynamic transmission electron microscope (DTEM) constructed at Lawrence Livermore National Laboratory, the rapid nucleation events occurring from pulsed laser irradiation can be directly observed and nucleation rates can be quantified. This paper briefly explains the DTEM approach and how it used to investigate the pulsed laser induced crystallization processes in NiTi and to determine kinetic parameters.},
doi = {},
url = {https://www.osti.gov/biblio/983387}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Mar 01 00:00:00 EST 2010},
month = {Mon Mar 01 00:00:00 EST 2010}
}

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