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Title: In situ TEM straining of nanograined free-standing thin films reveals various unexpected deformation mechanisms.

Abstract

In-situ transmission electron microscopy (TEM) straining experiments provide direct detailed observation of the deformation and failure mechanisms active at a length scale relevant to nanomaterials. This presentation will detail continued investigations into the active mechanisms governing high purity nanograined pulsed-laser deposited (PLD) nickel, as well as recent work into dislocation-particle interactions in nanostructured PLD aluminum-alumina alloys. Straining experiments performed on nanograined PLD free-standing nanograined Ni films with an engineered grain size distribution revealed that the addition of ductility with limited decrease in strength, reported in such metals, can be attributed to the simultaneous activity of three deformation mechanisms in front of the crack tip. At the crack tip, a grain agglomeration mechanism occurs where several nanograins appear to rotate, resulting in a very thin, larger grain immediately prior to failure. In the classical plastic zone in front of the crack tip, a multitude of mechanisms were found to operate in the larger grains including: dislocation pile-up, twinning, and stress-assisted grain growth. The region outside of the plastic zone showed signs of elasticity with limited indications of dislocation activity. The insight gained from in-situ TEM straining experiments of nanograined PLD Ni provides feedback for models of the deformation and failure inmore » nanograined FCC metals, and suggests a greater complexity in the active mechanisms. The investigation into the deformation and failure mechanisms of FCC metals via in-situ TEM straining experiments has been expanded to the effect of hard particles on the active mechanisms in nanograined aluminum with alumina particles. The microstructures investigated were developed with varying composition, grain size, and particle distribution via tailoring of the PLD conditions and subsequent annealing. In order to develop microstructures suitable for in-situ deformation testing, in-situ TEM annealing experiments were performed, revealing the effect of nanoparticle precipitates on grain growth. These films were then strained in the TEM and the resulting microstructural evolution will be discussed. In-situ TEM straining experiments currently provide a wealth of information into plasticity within nanomaterials and can potentially, with further development of TEM and nanofabrication tools, provide even greater investigative capabilities.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Sandia National Laboratories
Sponsoring Org.:
USDOE
OSTI Identifier:
1001009
Report Number(s):
SAND2010-2358C
TRN: US201101%%754
DOE Contract Number:
AC04-94AL85000
Resource Type:
Conference
Resource Relation:
Conference: Proposed for presentation at the In situ Transmission Electron Microscopy and Spectrometry Conference held April 6, 2010 in San Francisco, CA.
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; THIN FILMS; TRANSMISSION ELECTRON MICROSCOPY; IN-SITU PROCESSING; STRAINS; NANOSTRUCTURES; NICKEL; ALUMINIUM ALLOYS; ALUMINIUM OXIDES; DISLOCATIONS; DUCTILITY; TWINNING; GRAIN GROWTH; MORPHOLOGICAL CHANGES

Citation Formats

Follstaedt, David Martin, Knapp, James Arthur, Clark, Blythe G., Hattar, Khalid M., and Robertson, Ian M. In situ TEM straining of nanograined free-standing thin films reveals various unexpected deformation mechanisms.. United States: N. p., 2010. Web.
Follstaedt, David Martin, Knapp, James Arthur, Clark, Blythe G., Hattar, Khalid M., & Robertson, Ian M. In situ TEM straining of nanograined free-standing thin films reveals various unexpected deformation mechanisms.. United States.
Follstaedt, David Martin, Knapp, James Arthur, Clark, Blythe G., Hattar, Khalid M., and Robertson, Ian M. Thu . "In situ TEM straining of nanograined free-standing thin films reveals various unexpected deformation mechanisms.". United States. doi:.
@article{osti_1001009,
title = {In situ TEM straining of nanograined free-standing thin films reveals various unexpected deformation mechanisms.},
author = {Follstaedt, David Martin and Knapp, James Arthur and Clark, Blythe G. and Hattar, Khalid M. and Robertson, Ian M.},
abstractNote = {In-situ transmission electron microscopy (TEM) straining experiments provide direct detailed observation of the deformation and failure mechanisms active at a length scale relevant to nanomaterials. This presentation will detail continued investigations into the active mechanisms governing high purity nanograined pulsed-laser deposited (PLD) nickel, as well as recent work into dislocation-particle interactions in nanostructured PLD aluminum-alumina alloys. Straining experiments performed on nanograined PLD free-standing nanograined Ni films with an engineered grain size distribution revealed that the addition of ductility with limited decrease in strength, reported in such metals, can be attributed to the simultaneous activity of three deformation mechanisms in front of the crack tip. At the crack tip, a grain agglomeration mechanism occurs where several nanograins appear to rotate, resulting in a very thin, larger grain immediately prior to failure. In the classical plastic zone in front of the crack tip, a multitude of mechanisms were found to operate in the larger grains including: dislocation pile-up, twinning, and stress-assisted grain growth. The region outside of the plastic zone showed signs of elasticity with limited indications of dislocation activity. The insight gained from in-situ TEM straining experiments of nanograined PLD Ni provides feedback for models of the deformation and failure in nanograined FCC metals, and suggests a greater complexity in the active mechanisms. The investigation into the deformation and failure mechanisms of FCC metals via in-situ TEM straining experiments has been expanded to the effect of hard particles on the active mechanisms in nanograined aluminum with alumina particles. The microstructures investigated were developed with varying composition, grain size, and particle distribution via tailoring of the PLD conditions and subsequent annealing. In order to develop microstructures suitable for in-situ deformation testing, in-situ TEM annealing experiments were performed, revealing the effect of nanoparticle precipitates on grain growth. These films were then strained in the TEM and the resulting microstructural evolution will be discussed. In-situ TEM straining experiments currently provide a wealth of information into plasticity within nanomaterials and can potentially, with further development of TEM and nanofabrication tools, provide even greater investigative capabilities.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Apr 01 00:00:00 EDT 2010},
month = {Thu Apr 01 00:00:00 EDT 2010}
}

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