Effect of Dislocation Sources on Slip in Fe2Nb Laves Phase with Ni in Solution

2012 ◽  
Vol 1516 ◽  
pp. 269-274 ◽  
Author(s):  
N. Takata ◽  
H. Ghassemi-Armaki ◽  
Y. Terada ◽  
M. Takeyama ◽  
S. Kumar
Keyword(s):  
Plastic Deformation ◽  
Basal Plane ◽  
Focused Ion Beam ◽  
Shear Failure ◽  
Ion Beam ◽  
Laves Phase ◽  
Lower Stress ◽  
Two Phase ◽  
Theoretical Shear Strength ◽  
Dislocation Sources

ABSTRACTWe have examined the compression response of a ternary Fe2Nb Laves phase by deforming micropillars with a diameter of ~2 μm produced by focused ion beam milling from a two-phase Fe-15Nb-40Ni (at.%) ternary alloy consisting of the Laves phase and γ-Fe. The Laves phase micropillars exhibit high strength of about 6 GPa (of the order of the theoretical shear strength of the material), followed by a burst of plastic strain and shear failure on the basal plane. If dislocation sources are introduced on a non-basal plane in the micropillars by nanoindentation prior to compression, yielding occurs at a significantly lower stress level of about 3 GPa and plastic deformation by slip proceeds on a pyramidal plane close to (-1-122). Furthermore, if regenerative dislocation sources for basal slip are present in the micropillar, the Laves phase can be continuously plastically deformed in a stable manner to at least 5% strain at a significantly lower stress of 800 MPa. We thus demonstrate the plastic deformation of this ternary Laves phase at the micron-scale at room temperature when sufficient dislocation sources are present.

The evaluation of the composition dependence of fracture toughness of Al3Nb alloys by using micro-size fracture testing

MRS Advances ◽  
2017 ◽  
Vol 2 (26) ◽  
pp. 1405-1410
Author(s):  
Nobuhiro Matsuzaki ◽  
Ken-ichi Ikeda ◽  
Seiji Miura ◽  
Nobuaki Sekido ◽  
Takahito Ohmura
Keyword(s):  
Fracture Toughness ◽  
Single Crystal ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Two Phase ◽  
Fracture Testing ◽  
Average Value ◽  
Chevron Notch ◽  
Polycrystalline Alloys ◽  
Oxidation Resistant

ABSTRACTAl3Nb is known as a high oxidation resistant material, while it is quite brittle. As the fracture toughness of Al3Nb single crystal and its dependence on the composition are not obtained, the micro-sized fracture testing proposed by Suzuki et al. was performed. Al3Nb single crystal micron-order size cantilevers with a chevron-notch were fabricated in a grain of two-phase polycrystalline alloys by using FIB (Focused Ion Beam). From the load-displacement curves during the bending by a nanoindenter, the average value of fracture toughness of Nb-rich Al3Nb is evaluated to be 2.90 MPam1/2, while the fracture toughness of Al-rich Al3Nb is also evaluated to be 2.82 MPam1/2. From this result, the fracture toughness of Al3Nb is less dependent on its Al/Nb ratio. Furthermore the fracture toughness of Al3 (Nb, V) was evaluated to be 2.82 MPam1/2.The fracture toughness of Al3Nb is seemingly insensitive to V addition.

Indentation plastic displacement field: Part I. The case of soft films on hard substrates

1999 ◽  
Vol 14 (6) ◽  
pp. 2196-2203 ◽  
Author(s):  
T. Y. Tsui ◽  
Joost Vlassak ◽  
William D. Nix
Keyword(s):  
Plastic Deformation ◽  
Cross Sections ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Porous Titanium ◽  
Titanium Layer ◽  
Plastic Deformation Behavior ◽  
Plastic Displacement ◽  
Film Substrate ◽  
Made In

The plastic deformation behavior of Knoop indentations made in a soft, porous titanium/aluminum multilayered thin film on a hard silicon substrate is studied through use of the focused-ion-beam milling and imaging technique. Pileup is observed for indentations with depths larger than 30% of the total film thickness. Analysis of the indentation cross sections shows that plastic deformation around the indentation is partly accommodated by the closing of the pores within the multilayers. This densification process reduces the amount of pileup formed below that predicted by finite element simulations. Experimental results show that the pileup is formed by an increase of the titanium layer thickness near the edges of the indentation. The thickness increase is largest near the film/substrate interface and decreases toward the surface of the multilayered film. The amount of normal compression near the center of the indenter is characterized, and it is demonstrated that the deformation becomes more nonuniform with increasing indentation depth.

Compression of Micro-pillars of a Long Period Stacking Ordered Phase in the Mg-Zn-Y system

2013 ◽  
Vol 1516 ◽  
pp. 151-156 ◽  
Author(s):  
Atsushi Inoue ◽  
Kyosuke Kishida ◽  
Haruyuki Inui ◽  
Koji Hagihara
Keyword(s):  
Basal Plane ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Deformation Bands ◽  
Axis Orientation ◽  
Lpso Phase ◽  
Long Period ◽  
Image Position ◽  
Micro Pillars ◽  
Loading Axis

ABSTRACTDeformation behavior of an 18R-type long period stacking ordered (LPSO) phase in the Mg-Zn-Y system was studied by micro-pillar compressions of single crystalline specimens prepared by focused ion beam (FIB) technique as a function of loading axis orientation and specimen dimensions. When the loading axis is inclined to the basal plane of the LPSO phase by 42°, basal slip of (0001)<11$\bar 2$0>-type is activated irrespective of the specimen dimensions. When the loading axis is parallel to the basal plane, the formation of thick deformation bands are observed for all specimens tested. Strong size-dependence of yield stress values is observed for both types of micro-pillar specimens with different loading axis orientations.

scholarly journals Micron-Scale Deformation: A Coupled In Situ Study of Strain Bursts and Acoustic Emission

2017 ◽  
Vol 23 (6) ◽  
pp. 1076-1081 ◽  
Author(s):  
Ádám István Hegyi ◽  
Péter Dusán Ispánovity ◽  
Michal Knapek ◽  
Dániel Tüzes ◽  
Kristián Máthis ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Acoustic Emission ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Data Sampling ◽  
Deformation Curves ◽  
High Data ◽  
Excellent Control ◽  
As Stress

AbstractPlastic deformation of micron-scale crystalline materials differs considerably from bulk samples as it is characterized by stochastic strain bursts. To obtain a detailed picture of the intermittent deformation phenomena, numerous micron-sized specimens must be fabricated and tested. An improved focused ion beam fabrication method is proposed to prepare non-tapered micropillars with excellent control over their shape. Moreover, the fabrication time is less compared with other methods. The in situ compression device developed in our laboratory allows high-accuracy sample positioning and force/displacement measurements with high data sampling rates. The collective avalanche-like motion of the dislocations is observed as stress decreases on the stress–strain curves. An acoustic emission (AE) technique was employed for the first time to study the deformation behavior of micropillars. The AE technique provides important additional in situ information about the underlying processes during plastic deformation and is especially sensitive to the collective avalanche-like motion of the dislocations observed as the stress decreases on the deformation curves.

scholarly journals Single-Wedge Lift-Out for Atom Probe Tomography Al/Ni Multilayers Specimen Preparation Based on Dual-Beam-FIB

Micromachines ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 35
Author(s):  
Yi Qiao ◽  
Yalong Zhao ◽  
Zheng Zhang ◽  
Binbin Liu ◽  
Fusheng Li ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Atom Probe ◽  
Vertex Angle ◽  
Specimen Preparation ◽  
Two Phase ◽  
Interface Composition ◽  
Damage Layer ◽  
Dual Beam ◽  
Relationship Of

Atomic probe tomography (APT) samples with Al/Ni multilayer structure were successfully prepared by using a focused ion beam (FIB), combining with a field emission scanning electron microscope, with a new single-wedge lift-out method and a reduced amorphous damage layer of Ga ions implantation. The optimum vertex angle and preparation parameters of APT sample were discussed. The double interdiffusion relationship of the multilayer films was successfully observed by the local electrode APT, which laid a foundation for further study of the interface composition and crystal structure of the two-phase composites.

Microscale Fracture Toughness Testing of TiAl PST Crystals

2008 ◽  
Vol 1128 ◽  
Author(s):  
Daisuke Miyaguchi ◽  
Masaaki Otsu ◽  
Kazuki Takashima ◽  
Masao Takeyama
Keyword(s):  
Fracture Toughness ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Testing Machine ◽  
Type Specimens ◽  
Toughening Mechanisms ◽  
Two Phase ◽  
Fracture Toughness Testing ◽  
Crack Wake ◽  
Toughness Testing

AbstractA microscale fracture testing technique has been applied to examine the fracture properties of lamellar in TiAl PST crystals. Micro-sized cantilever specimens with a size ˜ 10×20×50 μm3 were prepared from Ti-48Al two-phase single crystals (PST) lamellar by focused ion beam (FIB) machining. Notches with a width of 0.5 μm and a depth of 5 μm were also introduced into the specimens by FIB. Two types of notch directions (interlamellar and translamellar) were selected when introducing the notches. Fracture tests were successfully completed using a mechanical testing machine for micro-sized specimens at room temperature. The fracture toughness (KQ) values of the interlamellar type specimens were obtained in the range 1.5–3.6 MPam1/2, while those of the translamellar specimens were 5.0–8.1 MPam1/2. These fracture toughness values are lower than those having been previously reported in conventional TiAl PST samples. For macro-sized specimens, extrinsic toughening mechanisms, including shear ligament bridging, act in the crack wake, and the crack growth resistance increases rapidly with increasing length of crack wake for lamellar structured TiAl alloys. In contrast, the crack length in microsized specimens is only 2–3 μm. This indicates that extrinsic toughening mechanisms are not activated in micro-sized specimens. This also indicates that intrinsic fracture toughness can be evaluated using microscale fracture toughness testing.

Nanostructuring the graphite basal plane by focused ion beam patterning and oxygen etching

2006 ◽  
Vol 17 (23) ◽  
pp. 5889-5894 ◽  
Author(s):  
Artur Böttcher ◽  
Moritz Heil ◽  
Ninette Stürzl ◽  
Stefan S Jester ◽  
Sharali Malik ◽  
...  
Keyword(s):  
Basal Plane ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Graphite Basal Plane ◽  
Ion Beam Patterning ◽  
Oxygen Etching

Indentation plastic displacement field: Part II. The case of hard films on soft substrates

1999 ◽  
Vol 14 (6) ◽  
pp. 2204-2209 ◽  
Author(s):  
T. Y. Tsui ◽  
Joost Vlassak ◽  
William D. Nix
Keyword(s):  
Plastic Deformation ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Mechanical Damage ◽  
Multilayered Film ◽  
Milling Method ◽  
Bulk Substrate ◽  
Small Change ◽  
Plastic Displacement ◽  
Made In

The plastic displacements around Knoop indentations made in hard titanium/aluminum multilayered films on soft aluminum alloy substrates have been studied. Indentations were cross-sectioned and imaged using focused-ion-beam (FIB) milling and high-resolution scanning electron microscopy (SEM), respectively. The FIB milling method has the advantage of removing material in a localized region without producing mechanical damage to the specimen. The micrographs of the cross-sectioned indentations indicate that most of the plastic deformation around the indentation is dominated by the soft aluminum substrate. There is a very small change in the multilayered film thickness around the indentation—less than 10%. The plastic deformation of the thin film resembles a membrane being deflected by a localized pressure gradient across the membrane. Stress-induced voids are also observed in the multilayered film, especially in the area around the indentation apex. The density and the size of the voids increase with indentation depth. Indentation sink-in effects are observed in all of the indentations inspected. Based on the experimental results, the amount of sink-in of the hard film–soft substrate composite is larger than the bulk substrate and film alone. This is confirmed by the finite element analyses conducted in this work.

Microstructure Change of B2 Precipitates in an Fe-Al-Ni Alloy due to Two-Step Heat-Treatment

2012 ◽  
Vol 706-709 ◽  
pp. 2496-2501
Author(s):  
Junji Yamanaka ◽  
Chiaya Yamamoto ◽  
Yasuhiro Kuno ◽  
Minoru Doi
Keyword(s):  
Focused Ion Beam ◽  
Early Stage ◽  
Ion Beam ◽  
Complex Structure ◽  
Two Phase ◽  
Microstructure Change ◽  
Ni Alloy ◽  
Scanning Transmission ◽  
The Matrix ◽  
The Face

We have been studying the microstructure change of B2 cubic precipitates into an A2+B2 complex structure in Fe-Al-Ni alloy. In this study, we carried out detailed observation using focused ion beam (FIB) and scanning transmission electron microscopy (STEM). First, Fe-14.3at%Al-10.3at%Ni solid solution was prepared. Secondly, the specimens were heated at 1173 K, at which they formed B2 cubic precipitates (ordered bcc) dispersed in an A2 matrix (disordered bcc). After that, the B2/A2 two-phase specimen was annealed at 973 K. Then we fabricated STEM specimens using FIB, followed by high-resolution secondary electron imaging. We repeated this slice-and-observation procedure to determine the detailed microstructure of this heat-treated alloy. At the early stage of the 973 K annealing, the A2 phase appeared in the original B2 precipitates and showed a spongelike structure, whereas small nanometer-order B2 particles appeared in the A2 matrix. The A2/B2 interface at this stage showed no anisotropic morphology. Therefore, the main driving force of this process may not be strain energy, but chemical and interface energies. Further annealing at 973 K decreased the number of small B2 particles in the A2 matrix, and these particles dissolved into the matrix eventually. The annealing also changed the A2/B2 spongelike structure, which was observed in the original B2 precipitates, into simple structures such as the A2 core and B2 crust. Then the B2 phase showed ordinal coarsening behavior. When B2 precipitates, which had hollow cubic morphology, were observed to be very close to each other, the face-centered area of the B2 crust tended to dissolve and only large B2 precipitates remained.

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