skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: In situ TEM investigation into the thermal stability of nanograined FCC metals.

Abstract

Nanostructured materials often display very unique properties related to their far-from-equilibrium nature. Due to these unique structures, many of these materials transform into other, more stable microstructures with minimal thermal excitation. This work will highlight examples of the unexpected routes taken during the microstructural evolution of pulsed-laser deposited (PLD) free-standing face-centered cubic (FCC) thin films as a function of deposition condition and annealing temperatures. A direct comparison between the grain growth dynamics observed during in situ TEM annealing experiments in PLD films of high-purity aluminum, copper, gold and nickel films, as well as aluminum-alumina alloys shows a multitude of kinetics. For high-purity systems film thickness, void density, grain size distribution, and deposition temperature were found to be the primary factors observed controlling the rate, extent, and nature of the grain growth. The growth dynamics ranged from nearly classical normal grain growth to abnormal grain growth resulting in a bimodal grain size distribution. The grain growth rate was found to be highly dependent on the materials system despite all of the films being nanograined FCC metals produced by similar PLD parameters. The investigation of the aluminum-alumina alloys produced under various compositions and deposition parameters suggests that particle pinning can be usedmore » to maintain nanostructured films, even after annealing treatments at high homologous temperatures. In addition to investigating the grain growth dynamics and the resulting grain size distribution, the variety of internal microstructures formed from thermal annealing were evaluated. These structures ranged from intergranular voids to stacking-fault tetrahedra. An unexpected, metastable hexagonal-closed packed phase was indentified in the high-purity nickel films. These in situ TEM observations have provided key insight into the microstructural evolution of nanograined free-standing metal films and the defect structure present in the grains resulting from various growth dynamics, in addition to suggesting multiple methods to tailor the structure and the resulting properties of nanostructured free-standing films.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Sandia National Laboratories
Sponsoring Org.:
USDOE
OSTI Identifier:
1028397
Report Number(s):
SAND2010-7340C
TRN: US201122%%265
DOE Contract Number:
AC04-94AL85000
Resource Type:
Conference
Resource Relation:
Conference: Proposed for presentation at the AVS National Meeting held October 18-22, 2010 in Albuquerque, NM.
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALLOYS; ALUMINIUM; ANNEALING; COPPER; DEFECTS; DEPOSITION; DISTRIBUTION; EXCITATION; GOLD; GRAIN GROWTH; GRAIN SIZE; KINETICS; NICKEL; STABILITY; THICKNESS; THIN FILMS

Citation Formats

Follstaedt, David Martin, Knapp, James Arthur, Hattar, Khalid Mikhiel, Kacher, Josh, Robertson, Ian M., and Brewer, Luke N. In situ TEM investigation into the thermal stability of nanograined FCC metals.. United States: N. p., 2010. Web.
Follstaedt, David Martin, Knapp, James Arthur, Hattar, Khalid Mikhiel, Kacher, Josh, Robertson, Ian M., & Brewer, Luke N. In situ TEM investigation into the thermal stability of nanograined FCC metals.. United States.
Follstaedt, David Martin, Knapp, James Arthur, Hattar, Khalid Mikhiel, Kacher, Josh, Robertson, Ian M., and Brewer, Luke N. Fri . "In situ TEM investigation into the thermal stability of nanograined FCC metals.". United States. doi:.
@article{osti_1028397,
title = {In situ TEM investigation into the thermal stability of nanograined FCC metals.},
author = {Follstaedt, David Martin and Knapp, James Arthur and Hattar, Khalid Mikhiel and Kacher, Josh and Robertson, Ian M. and Brewer, Luke N.},
abstractNote = {Nanostructured materials often display very unique properties related to their far-from-equilibrium nature. Due to these unique structures, many of these materials transform into other, more stable microstructures with minimal thermal excitation. This work will highlight examples of the unexpected routes taken during the microstructural evolution of pulsed-laser deposited (PLD) free-standing face-centered cubic (FCC) thin films as a function of deposition condition and annealing temperatures. A direct comparison between the grain growth dynamics observed during in situ TEM annealing experiments in PLD films of high-purity aluminum, copper, gold and nickel films, as well as aluminum-alumina alloys shows a multitude of kinetics. For high-purity systems film thickness, void density, grain size distribution, and deposition temperature were found to be the primary factors observed controlling the rate, extent, and nature of the grain growth. The growth dynamics ranged from nearly classical normal grain growth to abnormal grain growth resulting in a bimodal grain size distribution. The grain growth rate was found to be highly dependent on the materials system despite all of the films being nanograined FCC metals produced by similar PLD parameters. The investigation of the aluminum-alumina alloys produced under various compositions and deposition parameters suggests that particle pinning can be used to maintain nanostructured films, even after annealing treatments at high homologous temperatures. In addition to investigating the grain growth dynamics and the resulting grain size distribution, the variety of internal microstructures formed from thermal annealing were evaluated. These structures ranged from intergranular voids to stacking-fault tetrahedra. An unexpected, metastable hexagonal-closed packed phase was indentified in the high-purity nickel films. These in situ TEM observations have provided key insight into the microstructural evolution of nanograined free-standing metal films and the defect structure present in the grains resulting from various growth dynamics, in addition to suggesting multiple methods to tailor the structure and the resulting properties of nanostructured free-standing films.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Oct 01 00:00:00 EDT 2010},
month = {Fri Oct 01 00:00:00 EDT 2010}
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share:
  • Abstract not provided.
  • Abstract not provided.
  • 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 frontmore » 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.« less
  • No abstract prepared.
  • No abstract prepared.