Interdiffusion in Bimetallic Au-Fe Nanowhiskers Controlled by Interface Mobility

Qi, Yuanshen; Richter, Gunther; Suadiye, Eylül; Klinger, L.; Rabkin, Eugen

doi:10.2139/ssrn.3606808

Cited by 1 publication

(3 citation statements)

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“…The side facets of Au NWs are {111} and {100}, which are closest-packed and second closest-packed planes, respectively, of the face-centered cubic (FCC) lattice. The Fe layers adjacent to the {100} and {111} facets of the Au NW were found to be single-crystalline (SX) and polycrystalline (PX), respectively, and to form coherent SX Fe–Au and incoherent PX Fe–Au interfaces (see Figure S1 in Supporting Information and ref ( 38 )). The coherent interface exhibits the Bain orientation relationship between the SX Fe layer and the Au NW, for example, [01̅1] Au //[001] Fe , (011) Au //(010) Fe , and (100) Au //(100) Fe .…”

Section: Results and Discussionmentioning

confidence: 99%

“…Finally, we would like to emphasize that at relatively low temperatures and short annealing times employed in the in situ heating of NW#1 and NW#2, lattice diffusion of Fe into Au is very limited (as evidenced by the limited interface migration distance and formation of disconnections at the interface, see ref ( 38 )), therefore, the GB Kirkendall effect is the dominant factor in the plastic bending of the NWs when annealing was conducted below 500 °C.…”

Section: Results and Discussionmentioning

confidence: 99%

“…The preparation of Au/Fe bimetallic nanowhiskers (NWs) is described in detail in ref ( 38 ). In short, Au NWs attached to the W substrate were first fabricated employing the molecular beam epitaxy (MBE) method at the temperature of 800 °C and under vacuum of 5 × 10 –10 mbar.…”

Section: Methodsmentioning

confidence: 99%

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Plastic Forming of Metals at the Nanoscale: Interdiffusion-Induced Bending of Bimetallic Nanowhiskers

Richter

Suadiye

et al. 2020

ACS Nano

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Controlled plastic forming of nanoscale metallic objects by applying mechanical load is a challenge, since defect-free nanocrystals usually yield at near theoretical shear strength, followed by stochastic dislocation avalanches that lead to catastrophic failure or irregular, uncontrolled shapes. Herein, instead of mechanical load, we utilize chemical stress from imbalanced interdiffusion to manipulate the shape of nanowhiskers. Bimetallic Au–Fe nanowhiskers with an ultrahigh bending strength were synthesized employing the molecular beam epitaxy technique. The one-sided Fe coating on the defect-free, single-crystalline Au nanowhisker exhibited both single- and polycrystalline regions. Annealing the bimetallic nanowhiskers at elevated temperatures led to gradual change of curvature and irreversible bending. At low homological temperatures at which grain boundary diffusion is a dominant mode of mass transport this irreversible bending was attributed to the grain boundary Kirkendall effect during the diffusion of Au along the grain boundaries in the Fe layer. At higher temperatures and longer annealing times, the bending was dominated by intensive bulk diffusion of Fe into the Au nanowhisker, accompanied by a significant migration of the Au–Fe interphase boundary toward the Fe layers. The irreversible bending was caused by the concentration dependence of the lattice parameter of the Au(Fe) alloy and by the volume effect associated with the interphase boundary migration. The results of this study demonstrate a high potential of chemical interdiffusion in the controlled plastic forming of ultrastrong metal nanostructures. By design of the thickness, microstructure, and composition of the coating as well as the parameters of heat treatment, bimetallic nanowhiskers can be bent in a controlled manner.

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Section: Results and Discussionmentioning

confidence: 99%

Section: Results and Discussionmentioning

confidence: 99%