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.

Insights into the growth of bismuth nanoparticles on 2D structured BiOCl photocatalysts: an in situ TEM investigation

2015 ◽  
Vol 44 (36) ◽  
pp. 15888-15896 ◽  
Author(s):  
Xiaofeng Chang ◽  
Shuangbao Wang ◽  
Qi Qi ◽  
Mohammed A. Gondal ◽  
Siddique G. Rashid ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
In Situ Tem ◽  
Bismuth Nanoparticles ◽  
Transmission Electron

The formation and growth of bismuth nanoparticles onto BiOCl have been directly observed and characterized using a transmission electron microscope.

Dislocation–grain boundary interactions in martensitic steel observed through in situ nanoindentation in a transmission electron microscope

2004 ◽  
Vol 19 (12) ◽  
pp. 3626-3632 ◽  
Author(s):  
T. Ohmura ◽  
A.M. Minor ◽  
E.A. Stach ◽  
J.W. Morris
Keyword(s):  
Electron Microscope ◽  
Grain Boundary ◽  
Transmission Electron Microscope ◽  
Critical Stress ◽  
Martensitic Steel ◽  
High Angle ◽  
Block Boundary ◽  
Density Of Dislocations ◽  
Transmission Electron

Dislocation–interface interactions in Fe–0.4 wt% C tempered martensitic steel were studied through in situ nanoindentation in a transmission electron microscope (TEM). Two types of boundaries were imaged in the dislocated martensitic structure: a low-angle (probable) lath boundary and a coherent, high-angle (probable) block boundary. In the case of a low-angle grain boundary, the dislocations induced by the indenter piled up against the boundary. As the indenter penetrated further, a critical stress appeared to have been reached, and a high density of dislocations was suddenly emitted on the far side of the grain boundary into the adjacent grain. In the case of the high-angle grain boundary, the numerous dislocations that were produced by the indentation were simply absorbed into the boundary, with no indication of pileup or the transmission of strain. This surprising observation is interpreted on the basis of the crystallography of the block boundary.

In Situ Ultrahigh Vacuum Transmission Electron Microscope Investigations of Dynamical Changes of Nanostructures on Silicon

2006 ◽  
Vol 46 ◽  
pp. 111-119 ◽  
Author(s):  
Lih Juann Chen ◽  
Wen Wei Wu ◽  
C.H. Liu
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Ultrahigh Vacuum ◽  
In Situ Tem ◽  
Dynamic Changes ◽  
Directed Movement ◽  
Precise Knowledge ◽  
Transmission Electron ◽  
Unique Capability

In situ ultrahigh vacuum transmission electron microscope (TEM) is a powerful tool to investigate the dynamic changes of nanostructures on silicon. By observing growth and phase transitions in situ, understanding of their mechanisms can be used to model relevant processes. With the precise knowledge of the changes occurred on an atomic level, accurate control of the growth process can be achieved. The dynamical changes occurred on the nano scale are often unexpected, which also underscores the importance of the approach. In this presentation, we highlight two examples to demonstrate the unique capability of in situ TEM to study the dynamical changes. The examples include collective movement of Au nanoparticles and directed movement of Au-Si droplets on Si bi-crystal.

scholarly journals An in situ transmission electron microscope investigation into grain growth and ordering of sputter-deposited nanocrystalline Ni3Al thin films

2002 ◽  
Vol 17 (8) ◽  
pp. 2085-2094 ◽  
Author(s):  
H. P. Ng ◽  
A. H. W. Ngan
Keyword(s):  
Electron Microscope ◽  
Grain Growth ◽  
Transmission Electron Microscope ◽  
Growth Kinetics ◽  
Abnormal Grain Growth ◽  
Face Centered Cubic ◽  
Transmission Electron ◽  
Sputter Deposited ◽  
Grain Growth Kinetics

The grain growth kinetics and ordering behavior of direct-current magnetron sputter-deposited Ni75at.%Al25at.% alloy films were investigated using in situ isothermal annealing in a transmission electron microscope. Both normal and abnormal grain growth modes were observed. The normal grain growth kinetics under isothermal heating from 300 to 700 °C were found to comply with the Burke law d = K/dn−1, where d is grain size and K and n are constants with respect to time. The grain boundary mobility parameter K was found to obey an Arrehnius rate law with an apparent activation energy of 1.6 eV, and n was found to increase gradually from 5.2 at 300 °C to 8.7 at 700 °C. Abnormal grain growth occurred at 500 °C or higher, and grain coalescence was identified as an important operative mechanism. It was also observed that the initially as-deposited state of the films was crystalline with a disordered face-centered-cubic structure, but ordering into the equilibrium L12 intermetallic structure followed from annealing at temperatures above approximately 500 °C.

In situ TEM observation of rebonding on fractured silicon carbide

Nanoscale ◽  
2018 ◽  
Vol 10 (14) ◽  
pp. 6261-6269 ◽  
Author(s):  
Zhenyu Zhang ◽  
Junfeng Cui ◽  
Bo Wang ◽  
Haiyue Jiang ◽  
Guoxin Chen ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Atomic Resolution ◽  
In Situ Tem ◽  
Novel Approach ◽  
Transmission Electron

A novel approach is developed using an eyebrow hair to pick up and transfer nanowires (NWs), in order to obtain in situ transmission electron microscope (TEM) images of the rebonding and self-matching of SFs at atomic resolution.

Study of Deformation Behavior of Ultrafine-grained Materials Through in Situ Nanoindentation in a Transmission Electron Microscope

2005 ◽  
Vol 20 (7) ◽  
pp. 1735-1740 ◽  
Author(s):  
M. Jin ◽  
A.M. Minor ◽  
D. Ge ◽  
J.W. Morris
Keyword(s):  
Electron Microscope ◽  
Grain Boundary ◽  
Transmission Electron Microscope ◽  
Deformation Behavior ◽  
Boundary Migration ◽  
Boundary Motion ◽  
Transmission Electron ◽  
Ultrafine Grained ◽  
Grain Boundary Motion

The mechanical properties of ultrafine-grained and nanograined materials have received a great deal of recent attention because of their unusual and promising values. However, some of the most important mechanisms of deformation remain unclear. In this work, the deformation behavior of ultrafine-grained Al films and ultrafine-grained Fe is studied through in situ nanoindentation in a transmission electron microscope. Deformation-induced coarsening by grain boundary migration was observed in the ultrafine-grained Al films during deformation at room temperature, whereas no grain boundary motion was found in ultrafine-grained Fe. The lack of grain boundary motion in Fe was attributed to the pinning effect of nano-sized particles at the Fe grain boundaries.

The Etching of Silicon by Oxygen Observed by in situ Tem

1991 ◽  
Vol 222 ◽  
Author(s):  
Frances M. Ross ◽  
J. Murray Gibson
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
In Situ Tem ◽  
Step Motion ◽  
Etching Mechanism ◽  
Transmission Electron ◽  
Macroscopic Parameters ◽  
Made In ◽  
Oxygen Etching

ABSTRACTWe describe observations made in situ in a modified UHV transmission electron microscope of the process of etching of the Si (111) surface by oxygen. Etching occurs by the motion of individual bilayer steps across the surface and by analysing the step motion we discuss the etching mechanism in the context of macroscopic parameters.

Dislocation structures in deformed Ni3Al

1989 ◽  
Vol 47 ◽  
pp. 304-305
Author(s):  
Raja Subramanian ◽  
I.M. Robertson ◽  
H.K. Birnbaum
Keyword(s):  
Boundary Layer ◽  
Electron Microscope ◽  
Grain Boundary ◽  
Transmission Electron Microscope ◽  
Cohesive Energy ◽  
Intermetallic Alloys ◽  
Transmission Electron ◽  
Deviation From Stoichiometry

The improvement of the ductility of Ni3Al by the addition of boron has revived interest in intermetallic alloys. Addition of up to about 500 wt. ppm of boron increases the ductility of Ni3Al by as much as 50%. This improvement is dependent on the deviation from stoichiometry with optimum effect being obtained for the Ni-rich composition. The ductility enhancement has been attributed to the boron increasing the cohesive energy of the grain boundary and to a disordered boundary layer easing the slip process through the grain boundary.The dislocation structures produced in deformed Ni3Al with and without boron has been examined in the transmission electron microscope . Samples were deformed to a 3 % strain in bulk form while others were deformed in situ in the transmission electron microscope. (Details of the in situ TEM straining technique can be found in ref.)

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