Indentation Techniques for the Study of Deformation Across Grain Boundaries

2003 ◽  
Vol 778 ◽  
Author(s):  
K. A. Nibur ◽  
D. F. Bahr
Keyword(s):  
Grain Boundaries ◽  
Nanocrystalline Materials ◽  
Orientation Imaging Microscopy ◽  
Slip Systems ◽  
Slip Direction ◽  
Force Microscopy ◽  
Orientation Imaging ◽  
Atomic Force ◽  
Slip Planes ◽  
Active Slip

AbstractThe mechanism by which deformation is transferred across grain boundaries and ways in which boundaries of different misorientations impact this process has been studied using indentation testing. This information could be useful in designing texture of nanocrystalline materials to maximize their mechanical properties for specific applications. Atomic force microscopy (AFM) and orientation imaging microscopy (OIM) has been combined to identify slip systems activated around indentations. When indentations are placed near grain boundaries, slip steps can be imaged on both sides of the boundary and the associated slip systems of each grain can be determined. Dislocation pile ups have been observed around indentations near boundaries which do not share a common slip direction with the active slip planes of either grain, and slip steps have been seen to traverse boundaries when these shared slip directions are present.

scholarly journals Observation of Localized Corrosion of Ni-Based Alloys Using Coupled Orientation Imaging Microscopy and Atomic Force Microscopy

1999 ◽  
Vol 586 ◽  
Author(s):  
Peter J. Bedrossian ◽  
Adam J. Schwartz ◽  
Mukul Kumar ◽  
Wayne E. King
Keyword(s):  
Grain Boundaries ◽  
Orientation Imaging Microscopy ◽  
Sample Surface ◽  
Localized Corrosion ◽  
Corrosive Environment ◽  
Force Microscopy ◽  
Special Boundaries ◽  
Orientation Imaging ◽  
Atomic Force ◽  
Topographic Measurement

ABSTRACTWe present a method for assessing the relative vulnerabilites of distinct classes of grain boundaries to localized corrosion. Orientation imaging microscopy provides a spatial map which identifies and classifies grain boundaries at a metal surface. Once the microstructure of a region of a sample surface has been characterized, a sample can be exposed to repeated cycles of exposure to a corrosive environment alternating with topographic measurement by an atomic force microscope in the same region in which the microstructure had been mapped. When this procedure is applied to Ni and Ni-based alloys, we observe enhanced attack at random grain boundaries relative to special boundaries and twins in a variety of environments.

scholarly journals Investigation of slip transmission behavior across grain boundaries in polycrystalline Ni3Al using nanoindentation

2004 ◽  
Vol 19 (1) ◽  
pp. 189-201 ◽  
Author(s):  
P.C. Wo ◽  
A.H.W. Ngan
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Strong Dependence ◽  
Contact Mode ◽  
Force Microscopy ◽  
Atomic Force ◽  
Slip Transfer ◽  
Slip Planes ◽  
Indentation Tests ◽  
Transfer Behavior

The influence of grain boundaries on material deformation in Ni3Al was investigated by relating the material pile-up at grain boundaries and the propagation of slip across grain boundaries to the misorientation between the corresponding grains. Indentation tests were carried out using micro- and nanoindentation at distances shorter than the radius of indent size from a grain boundary on Ni3Al. The indents were observed using scanning electron microscopy and non-contact-mode atomic force microscopy. Repeated experimentation did not reveal a rising trend of hardness near grain boundaries, indicating that hardness is not a sensitive parameter to measure grain boundary strengthening effects. However, it was observed that the slip transfer behavior across a grain boundary has a strong dependence on a local misorientation factor m′ relating the misorientation of slip planes and slip directions on either side of the grain boundary. This result agrees with the fundamental assumption in the physical explanation of the Hall–Petch effect.

Hydrogen Transport and Hydrogen-Assisted Cracking in SUS304 Stainless Steel During Deformation at Low Temperatures

2015 ◽  
Author(s):  
Lin Zhang ◽  
Bai An ◽  
Takashi Iijima ◽  
Chris San Marchi ◽  
Brian Somerday
Keyword(s):  
Stainless Steel ◽  
Hydrogen Embrittlement ◽  
Room Temperature ◽  
Hydrogen Release ◽  
Hydrogen Transport ◽  
Force Microscopy ◽  
Atomic Force ◽  
Strain Induced Martensite ◽  
Hydrogen Assisted Cracking ◽  
Slip Planes

The behaviors of hydrogen transport and hydrogen-assisted cracking in hydrogen-precharged SUS304 austenitic stainless steel sheets in a temperature range from 177 to 298 K are investigated by a combined tensile and hydrogen release experiment as well as magnetic force microscopy (MFM) based on atomic force microscopy (AFM). It is observed that the hydrogen embrittlement increases with decreasing temperature, reaches a maximum at around 218 K, and then decreases with further temperature decrease. The hydrogen release rate increases with increasing strain until fracture at room temperature but remains near zero level at and below 218 K except for some small distinct release peaks. The MFM observations reveal that fracture occurs at phase boundaries along slip planes at room temperature and twin boundaries at 218 K. The role of strain-induced martensite in the hydrogen transport and hydrogen embrittlement is discussed.

Imaging Electron Transport across Grain Boundaries in an Integrated Electron and Atomic Force Microscopy Platform: Application to Polycrystalline Silicon Solar Cells

2009 ◽  
Vol 1153 ◽  
Author(s):  
Manuel J Romero ◽  
Fude Liu ◽  
Oliver Kunz ◽  
Johnson Wong ◽  
Chun-Sheng Jiang ◽  
...  
Keyword(s):  
Thin Films ◽  
Atomic Force Microscopy ◽  
Solar Cells ◽  
Electron Transport ◽  
Grain Boundaries ◽  
Polycrystalline Silicon ◽  
High Energy ◽  
Dominant Factor ◽  
Force Microscopy ◽  
Atomic Force

AbstractWe have investigated the local electron transport in polycrystalline silicon (pc-Si) thin-films by atomic force microscopy (AFM)-based measurements of the electron-beam-induced current (EBIC). EVA solar cells are produced at UNSW by <i>EVAporation</i> of a-Si and subsequent <i>solid-phase crystallization</i>–a potentially cost-effective approach to the production of pc-Si photovoltaics. A fundamental understanding of the electron transport in these pc-Si thin films is of prime importance to address the factors limiting the efficiency of EVA solar cells. EBIC measurements performed in combination with an AFM integrated inside an electron microscope can resolve the electron transport across individual grain boundaries. AFM-EBIC reveals that most grain boundaries present a high energy barrier to the transport of electrons for both p-type and n-type EVA thin-films. Furthermore, for p-type EVA pc-Si, in contrast with n-type, charged grain boundaries are seen. Recombination at grain boundaries seems to be the dominant factor limiting the efficiency of these pc-Si solar cells.

Interrogation of Alumina Grain Boundaries using Atomic Force Microscopy

1999 ◽  
Vol 580 ◽  
Author(s):  
P.A. Tibble ◽  
B.R. Heywood ◽  
R. Richardson ◽  
P. Barnes
Keyword(s):  
Particle Size ◽  
Atomic Force Microscopy ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Preferential Growth ◽  
Polycrystalline Alumina ◽  
Present Evidence ◽  
Force Microscopy ◽  
Atomic Force ◽  
Uniform Growth

AbstractA number of MgO doped (3wt%) polycrystalline alumina samples were prepared. The preparation of these samples varied; different regimes for annealing (1500 – 1600°C) and a range of dwell times were examined. Atomic force microscopy (AFM) was used to study surface features. Information on grain boundary dimensions (depth, width) is presented along with a study of grain particle size. The growth of the grain boundaries was found to contradict Mullins' theory of uniform growth with time. We also present evidence for Ostwalds' ripening and the preferential growth of [001] oriented grains.

Investigation of Surface Grooves from Migrating Grain Boundaries

2002 ◽  
Vol 750 ◽  
Author(s):  
Nicole E. Munoz ◽  
Shelley R. Gilliss ◽  
N. Ravishankar ◽  
C. Barry Carter
Keyword(s):  
Atomic Force Microscopy ◽  
Grain Boundary ◽  
Light Microscopy ◽  
Grain Boundaries ◽  
High Purity ◽  
Moving Boundary ◽  
Migration Process ◽  
Force Microscopy ◽  
Atomic Force ◽  
And Migration

ABSTRACTVisible-light microscopy (VLM) and atomic-force microscopy (AFM) were used to study the progression of grain-boundary grooving and migration in high-purity alumina (Lucalox™). Groove profiles from the same grain boundaries were revisited using AFM following successive heat-treatments. The grooves measured from migrating grain boundaries were found to have asymmetric partial-angles compared to those measured from boundaries that did not migrate during the experiment. For a moving boundary, the grain with the larger partial-angle was consistently found to grow into the grain with the smaller partial-angle. Migrating boundaries were observed to leave behind remnant thermal grooves. The observations indicate that the boundary may be bowing out during the migration process.

The Half-Cycle Slip Activity of Persistent Slip Bands in Polycrystals

2007 ◽  
Vol 567-568 ◽  
pp. 123-127 ◽  
Author(s):  
A. Weidner ◽  
W. Tirschler ◽  
C. Blochwitz ◽  
Werner Skrotzki
Keyword(s):  
Volume Fraction ◽  
Half Cycle ◽  
Slip Systems ◽  
Large Scatter ◽  
Force Microscopy ◽  
Atomic Force ◽  
Slip Bands ◽  
Slip Activity ◽  
Persistent Slip Bands ◽  
Number Of Cycles

The development of the volume fraction of cumulated persistent slip bands (PSBs) in cyclically deformed nickel polycrystals was investigated in dependence on the number of cycles using scanning electron microscopy (SEM) and atomic force microscopy (AFM). It was shown that there is a large scatter of the volume fraction of PSBs from grain to grain. Three different tendencies for the development of the volume fraction with increasing number of cycles were distinguished. It was shown that there is a correlation of the orientation of the primary slip systems with the volume fraction of cumulated PSBs and the activation of PSBs during half-cycle deformation.

Growth of Boron Carbide Nanostructures on Silicon Using Hot Filament Chemical Vapour Deposition

2018 ◽  
Vol 42 (2) ◽  
pp. 73-76 ◽  
Author(s):  
Azadeh Jafari ◽  
Mohammad Mosavat ◽  
Alireza Meidanchi ◽  
H. Hossienkhani
Keyword(s):  
Boron Carbide ◽  
Grain Boundaries ◽  
Chemical Vapour Deposition ◽  
Vapour Deposition ◽  
Boron Concentration ◽  
Chemical Vapour ◽  
X Ray Diffraction ◽  
Force Microscopy ◽  
Atomic Force ◽  
Hot Filament

Boron carbide nanostructures were grown on Si wafers through introduction of a mixture of B2O3 dissolved in methanol using hot filament chemical vapour deposition. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), Raman spectroscopy and the four-point probe technique were applied to characterise the properties of the boron carbide nanostructures. The XRD results showed that two kinds of boron carbide chemical compounds (B4C and B2C2) were deposited and the effect of boron concentration was significant. The FESEM images showed that the boron carbide nanostructures are made of crystal clusters with a cauliflower-like shape, in which the grain boundaries appear more clearly with increasing boron concentration. In addition, the AFM results showed that the surface roughness of the boron carbide films decreased with increasing boron concentration due to grain boundary diffusivity. The Raman spectrum results confirmed the presence of a B4C network and G and D bands. The results of the four-point probe method indicated that samples with higher boron incorporation showed the lowest sheet resistance (0.06 ω sq−1), which may be because of the decrease in inter-grain boundaries caused by the larger cluster size. This study suggests that higher boron incorporation in boron carbide nanostructures results in larger crystal clusters, higher thickness and lower film resistivity.

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