scholarly journals Deviating from the pure MAX phase concept: Radiation-tolerant nanostructured dual-phase Cr2AlC

2021 ◽  
Vol 7 (13) ◽  
pp. eabf6771
Author(s):  
M. A. Tunes ◽  
M. Imtyazuddin ◽  
C. Kainz ◽  
S. Pogatscher ◽  
V.M. Vishnyakov

A dual-phase Cr2AlC material was synthesized using magnetron sputtering at a temperature of 648 K. A stoichiometric and nanocrystalline MAX phase matrix was observed along with the presence of spherical-shaped amorphous nano-zones as a secondary phase. The irradiation resistance of the material was assessed using a 300-keV Xe ion beam in situ within a transmission electron microscope up to 40 displacements per atom at 623 K: a condition that extrapolates the harmful environments of future fusion and fission nuclear reactors. At the maximum dose investigated, complete amorphization was not observed. Scanning transmission electron microscopy coupled with energy-dispersive x-ray revealed an association between swelling due to inert gas bubble nucleation and growth and radiation-induced segregation and clustering. Counterintuitively, the findings suggest that preexisting amorphous nano-zones can be beneficial to Cr2AlC MAX phase under extreme environments.

Author(s):  
T. Yaguchi ◽  
M. Konno ◽  
T. Kamino ◽  
M. Ogasawara ◽  
K. Kaji ◽  
...  

Abstract A technique for preparation of a pillar shaped sample and its multi-directional observation of the sample using a focused ion beam (FIB) / scanning transmission electron microscopy (STEM) system has been developed. The system employs an FIB/STEM compatible sample rotation holder with a specially designed rotation mechanism, which allows the sample to be rotated 360 degrees [1-3]. This technique was used for the three dimensional (3D) elemental mapping of a contact plug of a Si device in 90 nm technology. A specimen containing a contact plug was shaped to a pillar sample with a cross section of 200 nm x 200 nm and a 5 um length. Elemental analysis was performed with a 200 kV HD-2300 STEM equipped with the EDAX genesis Energy dispersive X-ray spectroscopy (EDX) system. Spectrum imaging combined with multivariate statistical analysis (MSA) [4, 5] was used to enhance the weak X-ray signals of the doped area, which contain a low concentration of As-K. The distributions of elements, especially the dopant As, were successfully enhanced by MSA. The elemental maps were .. reconstructed from the maps.


Author(s):  
Dirk Doyle ◽  
Lawrence Benedict ◽  
Fritz Christian Awitan

Abstract Novel techniques to expose substrate-level defects are presented in this paper. New techniques such as inter-layer dielectric (ILD) thinning, high keV imaging, and XeF2 poly etch overflow are introduced. We describe these techniques as applied to two different defects types at FEOL. In the first case, by using ILD thinning and high keV imaging, coupled with focused ion beam (FIB) cross section and scanning transmission electron microscopy (STEM,) we were able to judge where to sample for TEM from a top down perspective while simultaneously providing the top down images giving both perspectives on the same sample. In the second case we show retention of the poly Si short after removal of CoSi2 formation on poly. Removal of the CoSi2 exposes the poly Si such that we can utilize XeF2 to remove poly without damaging gate oxide to reveal pinhole defects in the gate oxide. Overall, using these techniques have led to 1) increased chances of successfully finding the defects, 2) better characterization of the defects by having a planar view perspective and 3) reduced time in localizing defects compared to performing cross section alone.


2010 ◽  
Vol 16 (S2) ◽  
pp. 214-215
Author(s):  
T Tanigaki ◽  
K Ito ◽  
K Nakamura ◽  
Y Nagakubo ◽  
J Azuma ◽  
...  

Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.


Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1036 ◽  
Author(s):  
Shi-Hao Li ◽  
Jing-Ting Li ◽  
Wei-Zhong Han

Helium (He) bubbles are typical radiation defects in structural materials in nuclear reactors after high dose energetic particle irradiation. In the past decades, extensive studies have been conducted to explore the dynamic evolution of He bubbles under various conditions and to investigate He-induced hardening and embrittlement. In this review, we summarize the current understanding of the behavior of He bubbles in metals; overview the mechanisms of He bubble nucleation, growth, and coarsening; introduce the latest methods of He control by using interfaces in nanocrystalline metals and metallic multilayers; analyze the effects of He bubbles on strength and ductility of metals; and point out some remaining questions related to He bubbles that are crucial for design of advanced radiation-tolerant materials.


2008 ◽  
Vol 16 (1) ◽  
pp. 24-27 ◽  
Author(s):  
Haifeng Wang ◽  
Jason Fang ◽  
Jason Arjavac ◽  
Rudy Kellner

Automated scanning transmission electron microscopy (STEM) metrology provides critical dimension (CD) measurements an order of magnitude more precise than comparable scanning electron microscopy (SEM) measurements. New developments in automation now also provide throughput and response time sufficient to support high volume microelectronic manufacturing processes. The newly developed methodology includes automated, focused ion beam (FIB) based sample preparation; innovative, ex-situ sample extraction; and automated metrology. Although originally developed to control the production of thin film magnetic heads for data storage, the technique is fully applicable to any wafer-based manufacturing process.


2013 ◽  
Vol 762 ◽  
pp. 607-611 ◽  
Author(s):  
Guo Chao Wang ◽  
Jie Zhang ◽  
Xiao Wen Liu

The reaction process between Ti2AlC and Ag-Cu filler alloy was mentioned in our previous study. However, the reaction mechanism between Ti2AlC and filler alloy remained uncertain due to the existence of TiAl2, which was widely distributed in the dual-phase Ti2AlC substrate and exhibited intense reaction with Cu. In current research, pure-phase Ti2AlC was brazed to Cu using Ag-Cu filler alloy respectively at 850°C and 900°C for 10 min. First of all, to investigate the influence of TiAl2 on clarifying the reaction mechanism, Ti2AlC substrates with different component (single phase and dual phase) were joined to Cu at 850°C for comparison. However, in these joints, it was difficult to find any other reactant except for AlCu2Ti. Thus, the pure-phase Ti2AlC was brazed to Cu at 900°C, aiming to intensify the interaction between substrates and filler alloy. For characterizing the microstructure evolution in the joint, the typical region of the joint that contained all the reactants was selected and sliced by focused ion beam technology. Combining with transmission electron microscopy, all the decomposition products (e.g. Ti3AlC2 and TiC) in the joint were identified. Then the decomposition mechanism of Ti2AlC was clearly disclosed.


1991 ◽  
Vol 235 ◽  
Author(s):  
Daniel J. Kester ◽  
Russell Messier

ABSTRACTBoron nitride thin films were grown using ion beam assisted deposition. Boron metal was evaporated, and the depositing film was bombarded by nitrogen and argon ions. The films were characterized using Fourier transform infrared spectroscopy, electron diffraction, transmission electron microscopy, and Rutherford backscattering. The thin films were found to be cubic boron nitride, consisting of 100–200 Å crystallites with a small amount of an amorphous secondary phase. The best conditions for depositing cubic boron nitride were found to be a substrate temperature of 400°C, bombardment by a 50:50 mixture of argon and nitrogen with a bombarding ion energy of 500 eV and a ratio of bombarding ions to depositing boron atoms of from 1.0 to 1.5 ions per atom.


2016 ◽  
Vol 61 (2) ◽  
pp. 535-542 ◽  
Author(s):  
A. Kruk ◽  
G. Cempura ◽  
S. Lech ◽  
A. Czyrska -Filemonowicz

Abstract Allvac 718Plus (718Plus) is a high strength, corrosion resistant nickel- based superalloy used for application in power generation, aeronautics and aerospace industry. The 718Plus microstructure consists of a γ matrix with γ’-Ni3(Al,Ti) and some δ- Ni3Nb phases as well as lamellar particles (η-Ni3Ti, η*-Ni6AlNb or Ni6(Al,Ti)Nb) precipitated at the grain boundaries. The primary strengthening mechanism for this alloy is a precipitation hardening, therefore size and distribution of precipitates are critical for the performance of the alloy. The aim of this study was to characterize precipitates in the 718Plus superalloy using Scanning Transmission Electron Microscope combined with Energy Dispersive X-ray Spectroscopy (STEM-EDX) and Focused Ion Beam Scanning Electron Microscope (FIB-SEM). The STEM-EDX and FIB-SEM tomography techniques were used for 3D imaging and metrology of the precipitates. Transmission electron microscopy and EDX spectroscopy were used to reveal details of the 718Plus microstructure and allow determine chemical composition of the phases. The study showed that electron tomography techniques permit to obtain complementary information about microstructural features (precipitates size, shape and their 3D distribution) in the reconstructed volume with comparison to conventional particle analysis methods, e.g. quantitative TEM and SEM metallography


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