A <scp>MEMS</scp>‐based heating holder for the direct imaging of simultaneous <i>in‐situ</i> heating and biasing experiments in scanning/transmission electron microscopes

Mele, L.; Konings, Stan; Dona, Pleun; Evertz, Francis; Mitterbauer, Christoph; Faber, Pybe; Schampers, Ruud; Jinschek, Joerg R.

doi:10.1002/jemt.22623

Cited by 92 publications

(97 citation statements)

References 46 publications

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“…MEMS-based heating stages with fast thermal response (up to 10,000K/sec) and accurate temperature measurement [4] offer a powerful tool to monitor microstructure evolution during fast heating and cooling process. Here, we use (in situ) S/TEM methods to observe phase transformations in AM Ti64.…”

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confidence: 99%

In-situ TEM Heating Experiment to Study Effects of Cyclic Thermal Gradients on Ti-6Al-4V under Additive Manufacturing Growth Conditions

Shao

Frederick³

et al. 2018

Microsc Microanal

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Additive manufacturing (AM) [1] is a layer by layer manufacturing process, which is increasingly applied to produce parts and prototypes in automotive, aircraft and aerospace industry, as well as implants and prosthesis in biomechanical industry. In the AM process, a metal powder with targeted metal alloy composition is exposed to a scanning laser or electron beam, thereby experiencing a cyclic thermal process with large thermal gradients in rapid heating-cooling cycles. As an example, Ti-6Al-4V powder (AM Ti64) has been commercialized for laser-melting AM process [2] based on its special characteristics of a low weight ratio, as well as outstanding corrosion resistance, attractive for weight-reduction technology in transportation vehicles. However, in order to eventually replace established technology, it is necessary to understand properties of AM-produced parts based on the relationship between microstructure and processing parameters. Kenel.et [3] investigated phase transformation in AM Ti64 under laser melting and rapid cooling cycle by high-speed micro-X-ray diffraction (XRD) and ↔ β phase transformation was observed repeatedly.SEM-EDS mapping on pristine AM Ti64 (see Fig.1a) shows an average particle size of 30-40 m and confirms the average chemical composition [2]. SEM contrast changes on the sphere of the particle indicate presence of grain boundaries. Using focused ion beam (FIB) techniques, electron transparent lamellas have been extracted from these areas for further TEM investigations (see Fig.1b and 1c).TEM experiments (including in-situ heating) and STEM-EDS characterizations (Fig.2) are performed. The Bright Field TEM image (Fig.2a) and diffraction pattern on [0001] zone axis (Fig.2b) confirm the hexagonal-closed-packed (HCP)  phase of AM Ti64 at room temperature. STEM-EDS spectrum (Fig.2d) shows a uniform chemical composition.In-situ TEM heating experiment provide access to structure and dynamic behavior under AM processing conditions on the nanometer scale. MEMS-based heating stages with fast thermal response (up to 10,000K/sec) and accurate temperature measurement [4] offer a powerful tool to monitor microstructure evolution during fast heating and cooling process. Here, we use (in situ) S/TEM methods to observe phase transformations in AM Ti64.During the heating cycle at 990℃, primary HCP  phase transfers to body-centered-cubic (BCC)  phase. And in the subsequent cooling cycle, BCC  phase transfers to hexagonal ' martensite. STEM-EDS mapping across the grain boundaries will be used to understand if diffusion phenomena cause differences in elemental distribution. Finally, atomic scale S/TEM characterization will be conducted to observe dynamic changes and to understand solid/solid phase evolution and grain orientation in fast heatinghttps://doi

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confidence: 99%

In-situ TEM Heating Experiment to Study Effects of Cyclic Thermal Gradients on Ti-6Al-4V under Additive Manufacturing Growth Conditions

Shao

Frederick³

et al. 2018

Microsc Microanal

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“…However, quality of the EDS and EBSD data is influenced by infrared radiation interference at temperatures above 600°C. This background can be reduced to minimum by employing a microheatingplate device.A novel microheatingplate device based on microelectromechanical systems (MEMS) technology provides a maximum temperature of 1200°C and a very high heating/cooling rate in the order of 10 5 degrees per second [3]. This MEMS chip is able to support nano-scale to sub-millimeter-sized samples (samples with dimensions in tens of µm are typically used).…”

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New approaches to in-situ heating in FIB/SEM systems

Novák

Wandrol

et al. 2017

Microsc Microanal

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Over last decades significant effort has been made on in-situ heating experiments inside SEM and FIB/SEM chambers. Traditional way is to use low vacuum environment in the entire chamber. Although this valuable approach brings various undeniable advantages, new state of the art experiments coincide with new requirements, such as rapid changes in temperature, high-vacuum operation to maximize experiment cleanliness, ultra-high resolution SEM imaging and on top of it adaptable geometry in order to investigate sample's crystallography and composition changes using EBSD and EDS detectors. In this contribution we introduce an integration of two new modules fulfilling these requirements by allowing in-situ heating in FIB/SEM systems under high vacuum conditions. Moreover, heating in high vacuum combined with injection of selected gases was also proven capable of providing sample surfaceThe module choice essentially depends on the sample size and the type of analysis required. For millimeter-sized samples, a bulk heating stage can be selected, which allows a heating rate of unit degrees per second for heating up to 1000°C. The heating stage is made of materials with negligible outgassing that assures experiment cleanness and can also provide high vacuum environment arround the heated sample with SEM chamber pressure in the order of 10-5 Pa. In-situ observation of microstructure evolution can be achieved by standard SEM detectors collecting SE and BSE signal passing through a user replaceable heat shield, which protects sensitive parts in SEM chamber from overheating. In addition, geometry of a dedicated heat shield permits EBSD mapping as well as EDS analysis of a heated sample placed on this heating stage. However, quality of the EDS and EBSD data is influenced by infrared radiation interference at temperatures above 600°C. This background can be reduced to minimum by employing a microheatingplate device.A novel microheatingplate device based on microelectromechanical systems (MEMS) technology provides a maximum temperature of 1200°C and a very high heating/cooling rate in the order of 10 5 degrees per second [3]. This MEMS chip is able to support nano-scale to sub-millimeter-sized samples (samples with dimensions in tens of µm are typically used). In-situ imaging of samples placed on the MEMS chip during heating can be obtained using all types of detectors [4] including STEM, EBSD and EDS. The localised heating and small thermal mass capacity bear indespensible merits such as high uniformity of the heating area, high stability even during operations above 1000°C, site specification and minor sample displacement and drift stablilization. Chunk samples (typically metallic samples for Materials Science research) can be first fabricated using FIB milling in the bulk, then in-situ lifted out, welded on the MEMS chip and optionally the sample surface can be cleaned with low kV ions. We present in Figure 2 EBSD results of microstructure evolution of a slightly deformed Ti6Al4V chunk sample obtained during in-situ heating at ...

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“…Here we have compared the effects on mono-modal Ag NCs of electron beam heating and in-situ heating using a MEMS based heating stage [3] 1(a)-(c)), presumably due to surface diffusion of Ag underneath the capping layer. During subsequent in situ heating on the MEMS chip, however, the small Ag grains are re-absorbed by the NC, which then spheroidizes prior to sublimation.…”

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In Situ TEM Heating Experiments on PVP-Capped Silver Nano-Cubes

et al. 2016

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The accurate calibration of sample temperature for TEM heating stages is a prerequisite for reliable interpretation of data from in situ heating experiments. In a recent report, the size dependent sublimation behavior of Ag nanoparticles (NPs) exhibiting the Kelvin effect was used to determine the temperature of the membrane in contact with the NPs [1]. However, electron beam overheating of the NPs, which is directly proportional to the NP radius, could lead to an over-estimate of the sublimation temperature. As such, Ag NPs with a mono-modal particle size distribution would be ideal for in situ TEM temperature calibration experiments, because the NPs would exhibit a single well-defined sublimation temperature.The mechanism of sublimation in Ag nano-cubes (NCs), with a mono-modal size distribution [2] was investigated previously via in situ heating experiments in the TEM. However, it was found that the sublimation of the NCs could be influenced by interactions with the carbonaceous capping shell. This shell is typically made from poly-vinyl pyrolidone (PVP), which is used as a capping agent to stabilize the {100} planes of Ag and favor the formation of cuboidal NPs. A further complication arises due to the limited electronic conductivity of the capping shell, which could result in overheating of the Ag NCs under the electron beam. (Figures 1(a)-(c)), presumably due to surface diffusion of Ag underneath the capping layer. During subsequent in situ heating on the MEMS chip, however, the small Ag grains are re-absorbed by the NC, which then spheroidizes prior to sublimation. The morphological development during sublimation is different from that reported previously [2], suggesting that this may be related to the rupture of the capping shell along the sides of the NC. These data are compared with the sublimation temperature expected from the Kelvin effect to reveal the role of beam heating in the experiment. [4] References:[1] M

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A MEMS‐based heating holder for the direct imaging of simultaneous in‐situ heating and biasing experiments in scanning/transmission electron microscopes

Cited by 92 publications

References 46 publications

In-situ TEM Heating Experiment to Study Effects of Cyclic Thermal Gradients on Ti-6Al-4V under Additive Manufacturing Growth Conditions

In-situ TEM Heating Experiment to Study Effects of Cyclic Thermal Gradients on Ti-6Al-4V under Additive Manufacturing Growth Conditions

New approaches to in-situ heating in FIB/SEM systems

In Situ TEM Heating Experiments on PVP-Capped Silver Nano-Cubes

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