Application of the in situ TEM deformation technique to observe how “clean” and doped grain boundaries respond to local stress concentrations

1992 ◽  
Vol 40 (3) ◽  
pp. 330-338 ◽  
Author(s):  
I.M. Robertson ◽  
T.C. Lee ◽  
H.K. Birnbaum
Keyword(s):  
Grain Boundaries ◽  
Local Stress ◽  
In Situ Tem ◽  
Stress Concentrations

Grain Boundary Responses to Local and Applied Stress: An In Situ TEM Deformation Study

2006 ◽  
Vol 976 ◽  
Author(s):  
Bryan Miller ◽  
Jamey Fenske ◽  
Dong Su ◽  
Chung-Ming Li ◽  
Lisa Dougherty ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Transmission Electron Microscope ◽  
In Situ Tem ◽  
Deformation Twins ◽  
Transmission Electron ◽  
Dislocation Interactions

AbstractDeformation experiments at temperatures between 300 and 750 K have been performed in situ in the transmission electron microscope to investigate dislocation interactions and reactions with grain boundaries and other obstacles. Dislocations, both partial and perfect, as well as deformation twins have been observed being emitted from grain boundaries and, in some cases, even the same grain boundary. The ejection of dislocations from the grain boundary can result in its partial or total annihilation. In the latter case, the disintegration of the grain boundary was accompanied by grain growth and a change in misorientation.

In-Situ 1Mev Tem and Hrem Study of the Deformation and the Transformation of Symmetrical Tilt Grain Boundaries in Ge and Si.

1993 ◽  
Vol 319 ◽  
Author(s):  
Jany. Thibault ◽  
X. Baillin ◽  
J. Pelissier ◽  
J.L. Putaux ◽  
H.M. Michaud
Keyword(s):  
Grain Boundaries ◽  
Deformation Temperature ◽  
In Situ Tem ◽  
Final Structure ◽  
Different Types ◽  
Symmetrical Tilt ◽  
Misorientation Angles

AbstractThe evolution under deformation of symmetrical GBs in Si and Ge has been studied both by in-situ TEM and HREM. The influence of the strain conditions (tension or compression) on the final structure through the entrance of different types of dislocations will be discussed. The influence of the deformation temperature on the multiplicity of the structures has been observed in a particular range of misorientation angles.

An in-situ TEM study on the slip activation across grain boundaries

1990 ◽  
Vol 48 (4) ◽  
pp. 542-543
Author(s):  
T. C. Lee ◽  
I. M. Robertson ◽  
H. K. Birnbaum
Keyword(s):  
Stainless Steel ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Polycrystalline Material ◽  
In Situ Tem ◽  
310 Stainless Steel ◽  
Pile Up

The movement of lattice dislocations in a polycrystalline material is usually impeded by the existence of grain boundaries. Depending on the local chemistry and the structure of the boundary, this impediment (or the interaction of dislocations and grain boundaries) can create dislocation pile- ups and eventually lead to one of the several possible reactions: 1) dislocations can be transferred directly through the grain boundary, 2) dislocations can be absorbed and become grain boundary dislocations, 3) dislocations can be ejected back into their original grain, 4) dislocations can be accommodated in the grain boundary, followed by the emission dislocations into the adjoining grain or 5) nucleation of a crack at or near the intersection of the dislocation pile-up and the grain boundary.In order to understand the mechanism of the these interactions and their sensitivity to the chemistry of the grain boundary, the in-situ TEM straining technique has been used. The material studied were 310 stainless steel, hyper- and hypo-stoichiometric Ni3Al with and without boron.

Micromechanisms of Deformation and Fracture in Rapidly Solidified Ni3Al Alloys

1990 ◽  
Vol 213 ◽  
Author(s):  
G. Liu ◽  
G.M. Bond
Keyword(s):  
Dislocation Motion ◽  
In Situ Tem ◽  
Intermetallic Alloys ◽  
Stress Concentrations ◽  
X Ray ◽  
Deformation And Fracture ◽  
The Subject ◽  
Rapidly Solidified ◽  
Degree Of Order

ABSTRACTRapidly solidified Ni76 Al24 ribbons, with and without boron, have been the subject of in-situ TEM deformation studies, as well as X-ray and TEM characterization and TEM fractography. The aim has been to gain a better understanding of the influence of a reduced degree of order on grainboundary behavior and ductility. This, in turn, allows fresh insights to be gained, both into the manner in which boron additions can enhance ductility, and into the potential usefulness of sequential ordering in intermetallic alloys with a tendency to intergranular failure. Lower degrees of order are found to reduce stress concentrations at grain boundaries; this effect is due to easier generation of dislocations from boundary sources, and, to a lesser extent, the braking action of thermal APB's on dislocation motion. The beneficial effect of boron on ductility is seen to result, at least in part, from enhanced boundary cohesive strength.

Screen-printed nanocomposite sensors for online in situ structural health monitoring

2018 ◽  
Vol 33 (2) ◽  
pp. 236-253 ◽  
Author(s):  
Taimoor A Khan ◽  
Saad Nauman ◽  
Zeeshan Asfar ◽  
M Ali Nasir ◽  
Zaffar M Khan
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Local Stress ◽  
Stress Concentrations ◽  
Glass Fiber Reinforced Plastic ◽  
Structural Health ◽  
Nanocomposite Layer ◽  
Glass Fiber Reinforced ◽  
Screen Printed

In this article, we have explored screen printing as a fast and reliable process for the deposition of nanocomposite layer on glass fiber-reinforced plastic (GFRP) substrate for in situ structural health monitoring. The screen-printed sensor comprised of a thermoplastic matrix (high density polystyrene) and a dispersed nanofiller (carbon nanoparticles). Notches of different sizes (2.5 mm and 4.0 mm) were introduced to study the response of sensors to an existing damage. Stress concentrations were plotted across the width and the sensor results were correlated with the simulated stress concentrations to evaluate the response of sensors with respect to local stress concentrations. It was found that the screen-printed sensors responded to the stress concentrations since the layers were deposited in the vicinity of notches. The gauge factors altered due to the presence of notches indicating sensor sensitivity to the preexisting damage and resultant stress concentrations.

In situ TEM study of the effect of M/A films at grain boundaries on crack propagation in an ultra-fine acicular ferrite pipeline steel

2006 ◽  
Vol 54 (2) ◽  
pp. 435-443 ◽  
Author(s):  
Yong Zhong ◽  
Furen Xiao ◽  
Jingwu Zhang ◽  
Yiyin Shan ◽  
Wei Wang ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Grain Boundaries ◽  
Acicular Ferrite ◽  
Pipeline Steel ◽  
In Situ Tem

In Situ Observations of the Interaction of Liquid Lead Inclusions with Grain Boundaries in Aluminum

1998 ◽  
Vol 4 (3) ◽  
pp. 286-293 ◽  
Author(s):  
Heike Gabrisch ◽  
Ulrich Dahmen ◽  
Erik Johnson
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Ostwald Ripening ◽  
Wetting Transition ◽  
Liquid Lead ◽  
In Situ Tem ◽  
Triple Junctions ◽  
Temperature Range ◽  
In Situ Observations

The evolution of liquid lead (Pb) inclusions at grain boundaries in aluminum (Al) was investigated by direct in situ TEM observation in the temperature range from 330°–643°C, In agreement with earlier reports on quenched alloys, the characteristic contact angle of the lens-shaped grain boundary inclusions was found to be near 120°. This angle remained approximately constant over the entire temperature range, ruling out the possibility of a wetting transition. Coarsening of grain boundary inclusions was observed to proceed mainly by Ostwald ripening, although coalescence could also be observed. Inclusions at grain boundaries, at triple junctions, and at the intersection of grain boundaries with the foil surfaces adopted characteristic shapes that were shown to be equilibrium forms. At the highest temperatures, the grain boundaries were observed to detach from the inclusions and the interaction of a migrating grain boundary with inclusions could be observed.

scholarly journals Interaction between dislocations and Σ = 51 and Σ = 19 tilt grain boundaries in germanium: Study by in-situ, TEM and HREM

1993 ◽  
Vol 4 (2-3) ◽  
pp. 221-237 ◽  
Author(s):  
H.M. Michaud ◽  
X. Baillin ◽  
J. Pelissier ◽  
J.L. Putaux ◽  
J. Thibault
Keyword(s):  
Grain Boundaries ◽  
In Situ Tem
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