In situ TEM observations on morphological instability of ultrathin Pb films

Zhang, L.H; Sui, M. L.; Zhang, L; Hu, Kun; Li, D.X

doi:10.1016/j.msea.2003.08.126

Cited by 6 publications

(3 citation statements)

References 7 publications

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“…As the thickness of the films deceases to nanometric scale, the underlying surfaces as well as interfacial area become too large. [2][3][4][5] Therefore, the thermal stability of such a low-dimensional system against phase transformation relative to their bulk counterpart is of critical concern. [6,7] The phase transformation behavior of thin films can effectively be understood by studying the melting and solidification behavior.…”

Section: Introductionmentioning

confidence: 99%

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Melting Behavior of Al/Pb/Sn/Al Multilayered Thin Films

Khan

Devi

Biswas

2015

Metall Mater Trans A

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Metals or alloy nanoparticles (NPs) have been reported to exhibit superheating on melting when coated with higher melting point material or embedded in a matrix. This is due to the suppression of the heterogeneous nucleation of the melt at the epitaxial interface. For 2D thin films, this necessary condition is not feasible because even if a thin film is sandwiched between higher melting temperature materials with coherent interfaces, the heterogeneous nucleation of melt is possible at various detects. However, it has earlier been reported that 2D thin films of the pure metal sandwiched by other materials can exhibit superheating by suppression of melt growth. In order to probe this effect in case of alloy thin films, the present investigation has been carried out on Pb/Sn multilayers sandwiched between Al layers. The present study shows that such sandwiched thin films prepared by accumulative roll bonding process cause the formation of biphasic NPs in the intermixed region of Pb and Sn. Al layers undergo severe plastic deformation, leading to the generation of dislocations and sub-grain boundaries. DSC (differential canning calorimeter) thermograms of the films indicate superheating of 3 K to 6 K (or 3°C to 6°C). Theoretical analysis using currently available literatures has been carried out to justify the finding in the present investigation.

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Section: Introductionmentioning

confidence: 99%

“…Huge superheating is explained by suppression of the melt growth between the epitaxial layers during melting. [2,5] It has been suggested that the role of the epitaxial interfaces in case of Al/Pb/ Al multilayer thin film is mainly to suppress the melt growth. [1] The present investigation is primarily aimed to probe this effect on alloys.…”

Section: Introductionmentioning

confidence: 99%

Melting Behavior of Al/Pb/Sn/Al Multilayered Thin Films

Khan

Devi

Biswas

2015

Metall Mater Trans A

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“…The sintering process was recorded via a GATAN SC1000 ORIUS™ CCD camera at an image rate of approximately 20 frames-per-second. During the sintering process, collisions occurred and this resulted in coalescence of particles [1,2]. Figure 3 shows a sequence of HRTEM images in which the formation of a neck between adjoining nanoparticles is observed.…”

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confidence: 99%

In-situ TEM Observations on the Sintering Process of Colloidal Gold Using an Ultra-fast Heating Stage

et al. 2008

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A TEM heating stage with rapid heating and cooling capabilities has been developed by Protochips Inc., to enhance investigation of nanoscale phenomena. This stage introduces MEMS devices that provide millisecond heating with high stability. A prototype of this stage and one type of heating device are shown in Figures 1a and 1b, respectively. Heat is localized on a thin membrane at the center of the device, isolating the heat from surrounding mechanical parts, which minimizes drift even at high temperatures. A magnified image of the heating membrane is shown in Figure 1c. During operation, current is forced between the interdigitated electrodes and specimens are supported on carbon film and viewed through the holes etched in the membrane. Figure 2 shows drift in x and y as a function of time for heating to 900°C. It is observed that drift is approximately 1 µm in the x-direction and approximately 2.6 µm in the y-direction. The heating and quenching rate were determined by using a high speed camera, 5,000 frames-per-second. The center of the device reached white hot (~1,000°C) from room temperature in less of 1/1,000 s and cooled at the same rate. The use of MEMS membrane technology enables in situ heating experiments at temperatures as high as 1473K. The stability of this heating stage at high temperature enables atomic resolution images with minimal sample drift after a fast heating and quenching cycle.To demonstrate the capabilities of this new stage, sintering of colloidal gold nanoparticles was studied. The colloidal gold particles were deposited onto a "finger" device by drop-drying deposition. In-situ TEM and HRTEM observations were carried out on JEOL 2010 operating at 200 kV. The particles were heated to approximately 600°C. The sintering process was recorded via a GATAN SC1000 ORIUS™ CCD camera at an image rate of approximately 20 frames-per-second. During the sintering process, collisions occurred and this resulted in coalescence of particles [1,2]. Figure 3 shows a sequence of HRTEM images in which the formation of a neck between adjoining nanoparticles is observed. The sintering of metallic nanoparticles on a support is often modeled in terms of "Ostwald ripening", however, the results reveal a "neck growth" mechanism [3,4] dominated by surface atom diffusion rather than "Ostwald ripening".

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Experimental investigation of three-dimensional mixed-mode fracture of a titanium alloy at room and elevated temperatures

Zhang

Guo

et al. 2011

Sci. China Technol. Sci.

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Damage tolerance of titanium alloy structures is very important for the safety of modern aircraft under complex loading and environmental conditions. However, there is no available systematic knowledge about the effect of alloy thickness under mixed-mode loading at elevated temperatures. In the present study, a newly developed fracture experimental technique based on high-temperature moiré interferometry was employed to investigate experimentally I-II mixed-mode fracture in titanium alloy TC11 of various thicknesses at room and elevated temperatures. Compact shear specimens with thickness ranging from 1.8 to 7.1 mm were tested. The effects of temperature, thickness, and loading angle on the load capacity and crack initiation angle were investigated systematically. The TC11 alloy was shown to possess varied fracture performance at elevated temperature, and an opposite thickness effect at room temperature. Increasing temperature would enhance the fracture load capacity of thick specimens but reduce the fracture load capacity of thin specimens. Crack initiation angles under I-II mixed-mode loading showed the thickness-temperature coupling effects. These complex effects call for new development in three-dimensional mixed-mode fracture theory and technologies for damage tolerance assessment. mixed-mode fracture, titanium alloy, fracture toughness, crack initiation angle, thickness effect, high-temperature moiré interferometry Citation:Zhang S Q, Guo W L, Li H, et al. Experimental investigation of three-dimensional mixed-mode fracture of a titanium alloy at room and elevated temperatures.

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In situ TEM observations on morphological instability of ultrathin Pb films

Cited by 6 publications

References 7 publications

Melting Behavior of Al/Pb/Sn/Al Multilayered Thin Films

Melting Behavior of Al/Pb/Sn/Al Multilayered Thin Films

In-situ TEM Observations on the Sintering Process of Colloidal Gold Using an Ultra-fast Heating Stage

Experimental investigation of three-dimensional mixed-mode fracture of a titanium alloy at room and elevated temperatures

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