Quantitative in situ hot-stage high-resolution Transmission Electron Microscopy

Author(s):  
J. M. Howe

In situ hot-stage high-resolution transmission electron microscopy (HRTEM) provides unique capabilities for quantifying the dynamics of interfaces at the atomic level. Such information complements detailed static observations and calculations of interfacial structure, and is essential for understanding interface theory and solid-state phase transformations. This paper provides a brief description of particular requirements for performing in situ hot-stage HRTEM and illustrates the use of this technique to obtain quantitative data on the atomic mechanisms and kinetics of interface motion during precipitation of {111} θ phase in an Al-Cu-Mg-Ag alloy.The specimen and microscope requirements for in situ hot-stage HRTEM are not much different from those of static HRTEM, except that one must have a heating holder and equipment for recording and analyzing dynamic images. At present, most HRTEMs are equipped with a TV-rate camera, possibly combined with a charge-coupled device camera. An inexpensive way to record in situ HRTEM images is to send the output from the TV-rate camera directly into a standard VHS format videocassette recorder (VCR).

1994 ◽  
Vol 332 ◽  
Author(s):  
James M. Howe ◽  
W. E. Benson ◽  
A. Garg ◽  
Y.-C. Chang

ABSTRACTIn situ hot-stage high-resolution transmission electron microscopy (HRTEM) provides unique capabilities for quantifying the dynamics of interfaces at the atomic level. Such information is critical for understanding the theory of interfaces and solid-state phase transformations. This paper provides a brief description of particular requirements for performing in situ hot-stage HRTEM, summarizes different types of in situ HRTEM investigations and illustrates the use of this technique to obtain quantitative data on the atomic mechanisms and kinetics of interface motion in precipitation, crystallization and martensitic reactions. Some limitations of in situ hot-stage HRTEM and future prospects of this technique are also discussed.


1994 ◽  
Vol 357 ◽  
Author(s):  
A. J. Pedraza ◽  
Siqi Cao ◽  
L. F. Allard ◽  
D. H. Lowndes

AbstractA near-surface thin layer is melted when single crystal alumina (sapphire) is pulsed laserirradiated in an Ar-4%H2 atmosphere. γ-alumina grows epitaxially from the (0001) face of axalumina (sapphire) during the rapid solidification of this layer that occurs once the laser pulse is over. Cross sectional high resolution transmission electron microscopy (HRTEM) reveals that the interface between unmelted sapphire and γ-alumina is atomistically flat with steps of one to a few close-packed oxygen layers; however, pronounced lattice distortions exist in the resolidified γ-alumina. HRTEM also is used to study the metal-ceramic interface of a copper film deposited on a laser-irradiated alumina substrate. The observed changes of the interfacial structure relative to that of unexposed substrates are correlated with the strong enhancement of film-substrate bonding promoted by laser irradiation. HRTEM shows that a thin amorphous film is produced after irradiation of 99.6% polycrystalline alumina. Formation of a diffuse interface and atomic rearrangements that can take place in metastable phases contribute to enhance the bonding strength of copper to laser-irradiated alumina.


1993 ◽  
Vol 32 (Part 1, No. 6A) ◽  
pp. 2824-2831 ◽  
Author(s):  
Nobuyuki Ikarashi ◽  
Masaaki Tanaka ◽  
Toshio Baba ◽  
Hiroyuki Sakaki ◽  
Koichi Ishida

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