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Engineering interface structures and thermal stabilities via SPD processing in bulk nanostructured metals.

Zheng S, Carpenter JS, McCabe RJ, Beyerlein IJ, Mara NA - Sci Rep (2014)

Bottom Line: Here we show that the atomic structures of bi-metal interfaces in macroscale nanomaterials suitable for engineering structures can be significantly altered via changing the severe plastic deformation (SPD) processing pathway.Most importantly, the thermal stability of one is found to be significantly better than the other, indicating the exciting potential to control and optimize macroscale robustness via atomic-scale bimetal interface tuning.Taken together, these results demonstrate an innovative way to engineer pristine bimetal interfaces for a new class of simultaneously strong and thermally stable materials.

View Article: PubMed Central - PubMed

Affiliation: Center for Integrated Nanotechnologies, MPA-CINT, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.

ABSTRACT
Nanostructured metals achieve extraordinary strength but suffer from low thermal stability, both a consequence of a high fraction of interfaces. Overcoming this tradeoff relies on making the interfaces themselves thermally stable. Here we show that the atomic structures of bi-metal interfaces in macroscale nanomaterials suitable for engineering structures can be significantly altered via changing the severe plastic deformation (SPD) processing pathway. Two types of interfaces are formed, both exhibiting a regular atomic structure and providing for excellent thermal stability, up to more than half the melting temperature of one of the constituents. Most importantly, the thermal stability of one is found to be significantly better than the other, indicating the exciting potential to control and optimize macroscale robustness via atomic-scale bimetal interface tuning. Taken together, these results demonstrate an innovative way to engineer pristine bimetal interfaces for a new class of simultaneously strong and thermally stable materials.

No MeSH data available.


Outstanding thermal stability of nanomaterial strength and their interface structures.(a) Hardness reduction as a function of annealing temperature; (b) percentage increase in average layer thickness as a function of annealing temperatures; (c) typical HRTEM image of the 20 nm ARB-LR material after annealing at 600°C for one hour showing the same atomic faceted structure as before annealing (figure 2(c)); (c) typical HRTEM image of the 20 nm ARB-CR material after annealing at 600°C for one hour showing the same atomically flat structure as before annealing (figure 2(d)).
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f3: Outstanding thermal stability of nanomaterial strength and their interface structures.(a) Hardness reduction as a function of annealing temperature; (b) percentage increase in average layer thickness as a function of annealing temperatures; (c) typical HRTEM image of the 20 nm ARB-LR material after annealing at 600°C for one hour showing the same atomic faceted structure as before annealing (figure 2(c)); (c) typical HRTEM image of the 20 nm ARB-CR material after annealing at 600°C for one hour showing the same atomically flat structure as before annealing (figure 2(d)).

Mentions: At this point, we have demonstrated for the first time that two distinct atomically ordered interfaces can be created by altering the bulk mechanical processing pathway. To assess the quality of these interfaces, we test their stability in microstructure and hardness with respect to high temperature annealing. Figure 3a shows experimental results from nanoindentation tests before and after high-temperature annealing. Both materials maintain their high hardness, as well as their layered morphologies and layer thickness even after exposure to 500°C for one hour (supplementary figures 4b, 4f, 5c and 5d). This thermal stability far surpasses that of single-phase nanocrystalline Cu fabricated also by SPD techniques13. Materials made by non-equilibrium SPD techniques are expected to be thermally unstable because they contain high-energy interfaces1217. Remarkably, our SPD materials have an uncharacteristically high-temperature tolerance that is comparable to that of Cu-Nb nanolayered films fabricated via PVD23, which are comprised of low-energy, semi-coherent Cu-Nb interfaces. It is also superior to that of nano-twinned Cu, which contain a high density of low-energy, coherent twin boundaries33. Thus the two interfaces we have formed via mechanical means possess the same thermal stabilities as interfaces formed via thermal equilibrium processes such as PVD.


Engineering interface structures and thermal stabilities via SPD processing in bulk nanostructured metals.

Zheng S, Carpenter JS, McCabe RJ, Beyerlein IJ, Mara NA - Sci Rep (2014)

Outstanding thermal stability of nanomaterial strength and their interface structures.(a) Hardness reduction as a function of annealing temperature; (b) percentage increase in average layer thickness as a function of annealing temperatures; (c) typical HRTEM image of the 20 nm ARB-LR material after annealing at 600°C for one hour showing the same atomic faceted structure as before annealing (figure 2(c)); (c) typical HRTEM image of the 20 nm ARB-CR material after annealing at 600°C for one hour showing the same atomically flat structure as before annealing (figure 2(d)).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3936211&req=5

f3: Outstanding thermal stability of nanomaterial strength and their interface structures.(a) Hardness reduction as a function of annealing temperature; (b) percentage increase in average layer thickness as a function of annealing temperatures; (c) typical HRTEM image of the 20 nm ARB-LR material after annealing at 600°C for one hour showing the same atomic faceted structure as before annealing (figure 2(c)); (c) typical HRTEM image of the 20 nm ARB-CR material after annealing at 600°C for one hour showing the same atomically flat structure as before annealing (figure 2(d)).
Mentions: At this point, we have demonstrated for the first time that two distinct atomically ordered interfaces can be created by altering the bulk mechanical processing pathway. To assess the quality of these interfaces, we test their stability in microstructure and hardness with respect to high temperature annealing. Figure 3a shows experimental results from nanoindentation tests before and after high-temperature annealing. Both materials maintain their high hardness, as well as their layered morphologies and layer thickness even after exposure to 500°C for one hour (supplementary figures 4b, 4f, 5c and 5d). This thermal stability far surpasses that of single-phase nanocrystalline Cu fabricated also by SPD techniques13. Materials made by non-equilibrium SPD techniques are expected to be thermally unstable because they contain high-energy interfaces1217. Remarkably, our SPD materials have an uncharacteristically high-temperature tolerance that is comparable to that of Cu-Nb nanolayered films fabricated via PVD23, which are comprised of low-energy, semi-coherent Cu-Nb interfaces. It is also superior to that of nano-twinned Cu, which contain a high density of low-energy, coherent twin boundaries33. Thus the two interfaces we have formed via mechanical means possess the same thermal stabilities as interfaces formed via thermal equilibrium processes such as PVD.

Bottom Line: Here we show that the atomic structures of bi-metal interfaces in macroscale nanomaterials suitable for engineering structures can be significantly altered via changing the severe plastic deformation (SPD) processing pathway.Most importantly, the thermal stability of one is found to be significantly better than the other, indicating the exciting potential to control and optimize macroscale robustness via atomic-scale bimetal interface tuning.Taken together, these results demonstrate an innovative way to engineer pristine bimetal interfaces for a new class of simultaneously strong and thermally stable materials.

View Article: PubMed Central - PubMed

Affiliation: Center for Integrated Nanotechnologies, MPA-CINT, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.

ABSTRACT
Nanostructured metals achieve extraordinary strength but suffer from low thermal stability, both a consequence of a high fraction of interfaces. Overcoming this tradeoff relies on making the interfaces themselves thermally stable. Here we show that the atomic structures of bi-metal interfaces in macroscale nanomaterials suitable for engineering structures can be significantly altered via changing the severe plastic deformation (SPD) processing pathway. Two types of interfaces are formed, both exhibiting a regular atomic structure and providing for excellent thermal stability, up to more than half the melting temperature of one of the constituents. Most importantly, the thermal stability of one is found to be significantly better than the other, indicating the exciting potential to control and optimize macroscale robustness via atomic-scale bimetal interface tuning. Taken together, these results demonstrate an innovative way to engineer pristine bimetal interfaces for a new class of simultaneously strong and thermally stable materials.

No MeSH data available.