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

Title: Effects of solutes on the thermal stability of nanotwinned materials

Authors:
 [1];  [1];  [1]
  1. Ames Laboratory
Publication Date:
Research Org.:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1166891
Report Number(s):
IS-J 8478
Journal ID: ISSN 1478-6435
DOE Contract Number:
DE-AC02-07CH11358
Resource Type:
Journal Article
Resource Relation:
Journal Name: Philosophical Magazine (2003, Print); Journal Volume: 94; Journal Issue: 25
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; solute drag effect; molecular dynamics simulation; incoherent/coherent twin boundaries; nanotwins

Citation Formats

Borovikov, Valery, Mendelev, Mikhail I, and King, Alexander H. Effects of solutes on the thermal stability of nanotwinned materials. United States: N. p., 2014. Web. doi:10.1080/14786435.2014.937784.
Borovikov, Valery, Mendelev, Mikhail I, & King, Alexander H. Effects of solutes on the thermal stability of nanotwinned materials. United States. doi:10.1080/14786435.2014.937784.
Borovikov, Valery, Mendelev, Mikhail I, and King, Alexander H. Mon . "Effects of solutes on the thermal stability of nanotwinned materials". United States. doi:10.1080/14786435.2014.937784.
@article{osti_1166891,
title = {Effects of solutes on the thermal stability of nanotwinned materials},
author = {Borovikov, Valery and Mendelev, Mikhail I and King, Alexander H},
abstractNote = {},
doi = {10.1080/14786435.2014.937784},
journal = {Philosophical Magazine (2003, Print)},
number = 25,
volume = 94,
place = {United States},
year = {Mon Jul 28 00:00:00 EDT 2014},
month = {Mon Jul 28 00:00:00 EDT 2014}
}
  • High density grain boundaries provide high strength, but may introduce undesirable features, such as high Fermi levels and instability. We investigated the kinetics of recovery and recrystallization of Cu that was manufactured to include both nanotwins (NT) and high-angle columnar boundaries. We used the isothermal Johnson-Mehl-Avrami-Kolmogorov (JMAK) model to estimate activation energy values for recovery and recrystallization and compared those to values derived using the non-isothermal Kissinger equation. The JMAK model hinges on an exponent that expresses the growth mechanism of a material. The exponent for this Cu was close to 0.5, indicating low-dimensional microstructure evolution, which is associated withmore » anisotropic twin coarsening, heterogeneous recrystallization, and high stability. Since this Cu was of high purity, there was a negligible impurity-drag-effect on boundaries. The twin coarsening and heterogeneous recrystallization resulted from migration of high-angle columnar boundaries with their triple junctions in one direction, assisted by the presence of high concentration vacancies at boundaries. Analyses performed by electron energy loss spectroscopy of atomic columns at twin boundaries (TBs) and in the interior showed similar plasma peak shapes and L3 edge positions. As a result, this implies that values for conductivity and Fermi level are equal for atoms at TBs and in the interior.« less
  • In previous studies, strain-relaxation-induced changes in film microstructure, such as grain rotation, hillock formation, and dislocation slip bands, were observed after repeated thermal cycling between 298 and 4.2 K in 0.4-..mu..m-thick epsilon-phase Pb-Bi films that are used as the counterelectrode material of experimental Pb-alloy Josephson junction devices. In the present paper, the effects of small additions of Au (1--8 nm thickness) to the Pb-Bi films on the changes in the film microstructure were studied by using x-ray diffraction, and scanning and transmission electron microscopy. It was found that the changes in microstructure observed in the Pb-Bi films were significantly reducedmore » by the Au addition, although the average level of strain relaxation in the Pb-Bi alloy films upon thermal cycling between 298 and 4.2 K was not influenced by the Au addition. Experimental junctions were made using fine-grained Pb-In-Au films prepared at 77 K as the base electrode material, and Pb-Bi or Pb-Bi-Au films prepared at 273 K as the counterelectrode material. The junctions were cycled 200 times between 298 and 4.2 K. The junction failure level was observed to be reduced by a factor of approx.10 times compared to that of control samples by using Pb-Bi-Au films with 1-nm-thick Au as the counterelectrode material. An additional order of magnitude reduction in the junction failure level was obtained by increasing the Au thickness to 8 nm. The results indicate that reducing the changes in microstructure of the counterelectrode material reduces the incidence of junction failure upon repeated cycling between 298 and 4.2 K. However, adding Au to Pb-Bi counterelectrodes also causes an increase in the low-bias tunneling current. This increase in current, which is believed to be due to the presence of nonsuperconductive Pb/sub 3/Au compounds in the vicinity of the tunnel barrier, would be undesirable for some device applications.« less