Creep Deformation Microstructures in DS Nb-Hf-Ti-Si In-Situ Composites

1999 ◽  
Vol 5 (S2) ◽  
pp. 258-259
Author(s):  
S.D. Sitzman ◽  
B.P. Bewlay
Keyword(s):  
Creep Deformation ◽  
Microprobe Analysis ◽  
Electron Backscatter Diffraction ◽  
Czochralski Method ◽  
Directionally Solidified ◽  
Creep Tests ◽  
In Situ Composites ◽  
Before And After ◽  
Backscatter Diffraction

Directionally solidified (DS) in-situ composites based on (Nb) and (Nb) silicides, such as Nb5Si3 and Nb3Si, are presently under investigation as high-temperature structural materials [1, 2]. Alloying additions of elements such as Hf, Ti and Mo to these silicides are also being explored. The present paper describes the microstructure of a DS Nb-silicide based composite before and after creep deformation.Alloys were prepared from high purity elements (>99.9%) using induction levitation melting in a segmented water-cooled copper crucible. The alloys were directionally solidified using the Czochralski method [2]. Creep tests were conducted at 1200°C to 50% deformation. Characterization was performed using scanning electron microscopy, electron microprobe analysis (EMPA), and electron backscatter diffraction pattern analysis (EBSP).

Microstructural Response of DS Nb-Silicide In-Situ Composites During High-Temperature Creep Testing

2000 ◽  
Vol 6 (S2) ◽  
pp. 376-377
Author(s):  
B.P. Bewlay ◽  
S.D. Sitzman
Keyword(s):  
High Temperature ◽  
Electron Backscatter Diffraction ◽  
Czochralski Method ◽  
Longitudinal Section ◽  
Creep Testing ◽  
Directionally Solidified ◽  
Creep Tests ◽  
In Situ Composites ◽  
Structural Applications

Directionally solidified (DS) in-situ composites based on (Nb) and Nb silicides, such as Nb5Si3 and Nb3Si, are being investigated for high-temperature structural applications. The use of alloying additions, such as Hf, Ti and Mo, to these silicides is required to enhance their properties. The present paper describes the microstructural response of a DS Nb-silicide based composite to creep testing.The composites investigated were directionally solidified from a molten alloy using the Czochralski method as described previously. Creep tests were conducted at 1200°C to strains of up 50%. Microstructure and microtexture characterizations were performed using scanning electron microscopy, electron microprobe analysis (EMPA), and electron backscatter diffraction pattern analysis (EBSP).Microstructures of the longitudinal section of a DS composite generated from a Nb-12.5Hf-33Ti- 16Si alloy are shown in Figure 1 in the as-DS (left hand side) and the DS+creep tested conditions (right hand side).

Analyses of The Eutectoid Phase Transformation in Complex Ds Nb-Silicide In-Situ Composites

2001 ◽  
Vol 7 (S2) ◽  
pp. 1244-1245
Author(s):  
S.D. Sitzman ◽  
B.P. Bewlay
Keyword(s):  
Crystal Structure ◽  
Pattern Analysis ◽  
Electron Backscatter Diffraction ◽  
Czochralski Method ◽  
Directionally Solidified ◽  
Two Phase ◽  
In Situ Composites ◽  
Structural Applications ◽  
Backscatter Diffraction

In-situ composites based on (Nb) and Nb silicides, such as Nb5Si3 (tI32 crystal structure) and Nb3Si (tP32 crystal structure), are being investigated for revolutionary high-temperature structural applications [1,2]. The use of Hf and Ti alloying additions to these silicides has also been examined; in these systems Nb5Si3 has also been observed with the hP16 structure. The present paper describes EBSD analyses of a directionally solidified (DS) Nb-silicide based composite that experienced a eutectoid transformation. The composites were directionally solidified using the Czochralski method as described previously [1]. The composites were creep tested at 1200°C for 24 hours. Microstructure and microtexture characterization were performed using scanning electron microscopy, and electron backscatter diffraction pattern analysis (EBSD).The microstructure of a composite directionally solidified from a Nb-12.5Hf-33Ti-16Si alloy is shown in Figure 1. in the as-DS condition the microstructure consisted of primary (Nb)3Si dendrites and coarse (Nb)3Si-(Nb) two-phase cells.

Microstructure and Microtexture in Nb-Silicide Based Composites

1998 ◽  
Vol 4 (S2) ◽  
pp. 278-279
Author(s):  
B.P. Bewlay ◽  
J.A. Sutliff
Keyword(s):  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Czochralski Method ◽  
Phase Identification ◽  
Directionally Solidified ◽  
In Situ Composites ◽  
Back Scattering ◽  
Niobium Silicides ◽  
Microstructure And Microtexture

Directionally solidified in-situ composites based on niobium and niobium silicides, such as Nb5Si3 and Nb3Si, are presently under investigation as structural materials [1, 2], Alloying additions of elements such as Hf, Ti and Mo to these silicides are also being explored in order to increase strength and oxidation resistance. The present paper describes the effect of Hf, Mo and Ti additions on microstructure and microtexture of high temperature silcide-based in-situ composites.Alloys were prepared from high purity elements (>99.9%) using induction levitation melting in a segmented water-cooled copper crucible. The alloys were directionally solidified using the Czochralski method [2], Phase identification was performed using scanning electron microscopy, electron microprobe analysis (EMPA), and automated electron back scattering pattern (EBSP) analysis. Using EBSP, positive phase identification was accomplished by direct comparison of the location and character of the diffraction bands in the experimental pattern with those calculated from simulated patterns generated using the possible structure types.

Orientation and Microstructure Dependence of Electromigration Damage in Damascene Cu Interconnect Lines

2005 ◽  
Vol 495-497 ◽  
pp. 1443-1448 ◽  
Author(s):  
Kabir Kumar Mirpuri ◽  
Jerzy A. Szpunar
Keyword(s):  
Electron Backscatter Diffraction ◽  
Orientation Dependence ◽  
In Situ Monitoring ◽  
Cu Interconnects ◽  
Electron Backscatter ◽  
Before And After ◽  
Cu Interconnect ◽  
Interconnect Lines ◽  
Backscatter Diffraction

In the present paper we report the texture and microstructure dependence of electromigration damage in Cu interconnects. This was made possible by ncorporating a sophisticated set of instrumentation within the SEM which enabled in-situ monitoring of the electromigration defects. The electron backscatter diffraction (EBSD) maps were obtained before and after the completion of the electromigration tests. Thus, by comparing the maps before and after the failure it was possible to associate the texture and microstructure with both failure sites - voids and hillocks. Results from lines down to 130 nm are included and orientation dependence of the defects is discussed.

scholarly journals Deformation mechanism of neutron irradiated Al-B based on SEM-DIC

2022 ◽  
Vol 355 ◽  
pp. 01004
Author(s):  
Jiaqi Xiang ◽  
Qijie Feng ◽  
Junchao Cheng ◽  
Lei Lu ◽  
Junyu Huang ◽  
...  
Keyword(s):  
Slip Band ◽  
Electron Backscatter Diffraction ◽  
Image Correlation ◽  
High Concentration ◽  
Helium Bubbles ◽  
Band Area ◽  
Transmission Electron ◽  
Before And After ◽  
Backscatter Diffraction

The electron backscatter diffraction (EBSD) characterization of irradiated Al-B shows that there is a high concentration defect region around the borides. Nanoscale speckle particles were successfully prepared on the surface of Al-B before and after irradiation, and then the mesoscale strain during in-situ deformation was obtained by digital image correlation (DIC) technique. The results shows that slip band bypass such an area through cross slips with slip band deflection. Transmission electron microscopy (TEM) indicates that abundant helium bubbles exist in the deflected slip band area pinning the dislocations.

Grain Growth in Al: First Results from a Combined Study of Bulk and In-Situ Experiments Using a Columnar Structured Al Foil

2004 ◽  
Vol 467-470 ◽  
pp. 935-940 ◽  
Author(s):  
Sandra Piazolo ◽  
Vera G. Sursaeva ◽  
David J. Prior
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Electron Backscatter Diffraction ◽  
Boundary Energy ◽  
Complete Replacement ◽  
Von Neumann ◽  
In Situ Experiments ◽  
First Results ◽  
Backscatter Diffraction

First results from grain growth experiments in a columnar structured Al foil show several interesting features: (a) the grain size distribution remains heterogeneous even after up to 300 min. annealing and (b) the Von Neumann-Mullins relation is not always satisfied. To clarify the underlying reasons for these features, in-situ heating experiments within a Scanning Electron Microscope (SEM) were combined with detailed Electron Backscatter Diffraction (EBSD) analysis. These show that the movement of boundaries can be strongly heterogeneous. For example, the complete replacement of one grain by a neighbouring grain without significant change of the surrounding grain boundary topology is frequently seen. Experiments show that grain boundary energy and/or mobility are anisotropic both with respect to misorientation and orientation of grain boundary plane. Low energy and/or mobility boundaries are commonly low angle boundaries, twin boundaries and boundaries that form traces to a low index plane of at least one of the adjacent grains. As a consequence the Von Neumann-Mullins relation is not always satisfied.

scholarly journals Novel −75°C SEM cooling stage: application for martensitic transformation in steel

Microscopy ◽  
2020 ◽  
Author(s):  
Kaneaki Tsuzazki ◽  
Motomichi Koyama ◽  
Ryosuke Sasaki ◽  
Keiichiro Nakafuji ◽  
Kazushi Oie ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Electron Backscatter Diffraction ◽  
Dislocation Slip ◽  
In Situ Observation ◽  
Contrast Imaging ◽  
Cooling Stage ◽  
Electron Channelling ◽  
Electron Backscatter ◽  
Backscatter Diffraction

Abstract Microstructural changes during the martensitic transformation from face-centred cubic (FCC) to body-centred cubic (BCC) in an Fe-31Ni alloy were observed by scanning electron microscopy (SEM) with a newly developed Peltier stage available at temperatures to  −75°C. Electron channelling contrast imaging (ECCI) was utilized for the in situ observation during cooling. Electron backscatter diffraction analysis at ambient temperature (20°C) after the transformation was performed for the crystallographic characterization. A uniform dislocation slip in the FCC matrix associated with the transformation was detected at −57°C. Gradual growth of a BCC martensite was recognized upon cooling from −57°C to −63°C.

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