scholarly journals Deformation Mechanisms in Ni-Based Superalloys at Room and Elevated Temperatures Studied by In Situ Neutron Diffraction and Electron Microscopy

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 719
Author(s):  
Frank Kümmel ◽  
Andreas Kirchmayer ◽  
Cecilia Solís ◽  
Michael Hofmann ◽  
Steffen Neumeier ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Deformation Behavior ◽  
Elevated Temperatures ◽  
Tensile Deformation ◽  
Dislocation Motion ◽  
Microstructural Investigation ◽  
Neutron Diffractometer ◽  
Before And After ◽  
Lattice Planes

Polycrystalline Ni-based superalloys are one of the most frequently used materials for high temperature load-bearing applications due to their superior mechanical strength and chemical resistance. In this paper, we presented an in situ diffraction study on the tensile deformation behavior of the polycrystalline Ni-based superalloy VDM® Alloy 780 at temperatures up to 500 °C performed at the STRESS-SPEC neutron diffractometer at the Heinz Maier-Leibnitz Zentrum. A detailed microstructural investigation was carried out by electron microscopy before and after testing. The results of these studies allowed us to determine the deformation mechanism in the differently orientated grains. It is shown that the deformation behavior, which is mainly dislocation motion and shearing of the γ′-precipitates, does not change at this temperature range. The deformation is strongly anisotropic and depends on the grain orientation. The macroscopic hardening can mainly be attributed to plastic deformation in grains, where the (200) lattice planes were orientated perpendicular to the loading direction. Accordingly, a remaining lattice strain and high dislocation density were detected predominantly in these grains.

scholarly journals Study on Microstructure and In Situ Tensile Deformation Behavior of Fe-25Mn-xAl-8Ni-C Alloy Prepared by Vacuum Arc Melting

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 814
Author(s):  
Yaping Bai ◽  
Meng Li ◽  
Chao Cheng ◽  
Jianping Li ◽  
Yongchun Guo ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Deformation Behavior ◽  
Tensile Deformation ◽  
Austenite Phase ◽  
Vacuum Arc ◽  
Al Content ◽  
Arc Melting ◽  
Vacuum Arc Melting ◽  
Tensile Deformation Behavior

In this study, Fe-25Mn-xAl-8Ni-C alloys (x = 10 wt.%, 11 wt.%, 12 wt.%, 13 wt.%) were prepared by a vacuum arc melting method, and the microstructure of this series of alloys and the in situ tensile deformation behavior were studied. The results showed that Fe-25Mn-xAl-8Ni-C alloys mainly contained austenite phase with a small amount of NiAl compound. With the content of Al increasing, the amount of austenite decreased while the amount of NiAl compound increased. When the Al content increased to 12 wt.%, the interface between austenite and NiAl compound and austenitic internal started to precipitate k-carbide phase. In situ tensile results also showed that as the content of Al increased, the alloy elongation decreased gradually, and the tensile strength first increased and then decreased. When the Al content was up to 11 wt.%, the elongation and tensile strength were 2.6% and 702.5 MPa, respectively; the results of in situ tensile dynamic observations show that during the process of stretching, austenite deformed first, and crack initiation mainly occurred at the interface between austenite and NiAl compound, and propagated along the interface, resulting in fracture of the alloy.

In-situ tensile deformation behavior of powder metallurgy Ti6Al4V alloys

2020 ◽  
Vol 91 ◽  
pp. 105266
Author(s):  
Boxin Lu ◽  
Fang Yang ◽  
Yanru Shao ◽  
Xinyue Zhang ◽  
Cunguang Chen ◽  
...  
Keyword(s):  
Powder Metallurgy ◽  
Deformation Behavior ◽  
Tensile Deformation ◽  
Tensile Deformation Behavior

scholarly journals Temperature Calibration forIn SituEnvironmental Transmission Electron Microscopy Experiments

2015 ◽  
Vol 21 (6) ◽  
pp. 1622-1628 ◽  
Author(s):  
Jonathan P. Winterstein ◽  
Pin Ann Lin ◽  
Renu Sharma
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Elevated Temperatures ◽  
Lattice Parameter ◽  
Hydrogen Gas ◽  
Material Behavior ◽  
Sample Temperature ◽  
Transmission Electron ◽  
Local Sample

AbstractIn situenvironmental transmission electron microscopy (ETEM) experiments require specimen heating holders to study material behavior in gaseous environments at elevated temperatures. In order to extract meaningful kinetic parameters, such as activation energies, it is essential to have a direct and accurate measurement of local sample temperature. This is particularly important if the sample temperature might fluctuate, for example when room temperature gases are introduced to the sample area. Using selected-area diffraction (SAD) in an ETEM, the lattice parameter of Ag nanoparticles was measured as a function of the temperature and pressure of hydrogen gas to provide a calibration of the local sample temperature. SAD permits measurement of temperature to an accuracy of ±30°C using Ag lattice expansion. Gas introduction can cause sample cooling of several hundred degrees celsius for gas pressures achievable in the ETEM.

Tensile deformation behavior of superalloy 718 at elevated temperatures

2009 ◽  
Vol 471 (1-2) ◽  
pp. 331-335 ◽  
Author(s):  
Y. Wang ◽  
W.Z. Shao ◽  
L. Zhen ◽  
C. Yang ◽  
X.M. Zhang
Keyword(s):  
Deformation Behavior ◽  
Elevated Temperatures ◽  
Tensile Deformation ◽  
Tensile Deformation Behavior
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