The True Shape of Persistent Slip Markings in Fatigued Metals

2013 ◽  
Vol 592-593 ◽  
pp. 781-784 ◽  
Author(s):  
Jaroslav Polák ◽  
Jiří Man ◽  
Ivo Kuběna
Keyword(s):  
Focused Ion Beam ◽  
Early Stage ◽  
Ion Beam ◽  
Fatigue Crack Initiation ◽  
Stage Of Development ◽  
Persistent Slip Bands ◽  
True Shape ◽  
Relief Formation ◽  
316L Steel ◽  
Characteristic Features

Persistent slip markings (PSMs) were experimentally studied in 316L steel fatigued to early stages of the fatigue life. High resolution SEM, combined with focused ion beam (FIB) technique and atomic force microscopy (AFM) were used to assess the true shape of PSMs in their early stage of development. General features of PSMs in fatigued metals are extrusions and intrusions. Their characteristic features were determined. They were discussed in relation with the theories of surface relief formation and fatigue crack initiation based on the formation, migration and annihilation of point defects in the bands of intensive cyclic slip - persistent slip bands (PSBs)

AFM and FIB Study of Cyclic Strain Localization and Surface Relief Evolution in Fatigued f.c.c. Polycrystals

2014 ◽  
Vol 891-892 ◽  
pp. 524-529 ◽  
Author(s):  
Jiří Man ◽  
Miroslav Valtr ◽  
Ivo Kuběna ◽  
Martin Petrenec ◽  
Karel Obrtlík ◽  
...  
Keyword(s):  
Surface Relief ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Fatigue Crack Initiation ◽  
Cyclic Strain ◽  
Force Microscopy ◽  
Physically Based ◽  
Relief Formation ◽  
316L Steel ◽  
Different Temperatures

Atomic force microscopy (AFM) and focused ion beam technique (FIB) were adopted to study the early stages of surface relief evolution in 316L steel and polycrystalline copper fatigued with constant plastic strain amplitudes at different temperatures (316L steel at 93, 173 and 573 K; copper at 83, 173 and 295 K). Qualitative and quantitative data on the morphology and shape of persistent slip markings (PSMs), occurrence of extrusions and intrusions and the kinetics of extrusion growth are reported. They are discussed in relation with recent physically based theories of surface relief formation leading to fatigue crack initiation.

Slip Activity of Persistent Slip Bands in early Stages of Fatigue Life of Austenitic 316L Steel

2013 ◽  
Vol 592-593 ◽  
pp. 785-788
Author(s):  
Jiří Man ◽  
Anja Weidner ◽  
Petr Klapetek ◽  
Jaroslav Polák
Keyword(s):  
Fatigue Life ◽  
Plastic Strain ◽  
Early Stage ◽  
Fatigue Crack Initiation ◽  
Plastic Strain Amplitude ◽  
Slip Bands ◽  
Slip Activity ◽  
Persistent Slip Bands ◽  
316L Steel

Flat specimen of 316L steel was cyclically pre-deformed with constant plastic strain amplitude to early stage of fatigue life relevant to the period of cyclic strain localization and fatigue crack initiation. To document slip activity and reversibility/irreversibility of persistent slip bands (PSBs) in situ experiments in the high-resolution SEMFEG under special imaging conditions were performed. The half-and full-cycle slip activity and distribution of plastic strain within PSBs in individual grains were investigated via slip steps generated in half-and full-cycle deformation after intermediate vibration polishing. After completion of in situ tests the surface topography in identical locations was quantitatively documented using atomic force microscopy (AFM).

Surface Relief Formation in Relation to the Underlying Dislocation Arrangement

2016 ◽  
Vol 258 ◽  
pp. 526-529 ◽  
Author(s):  
Veronika Mazánová ◽  
Milan Heczko ◽  
Ivo Kuběna ◽  
Jaroslav Polák
Keyword(s):  
Electron Microscopy ◽  
Dislocation Structure ◽  
Fatigue Crack Initiation ◽  
Surface Profile ◽  
Specimen Surface ◽  
Slip Bands ◽  
Transmission Electron ◽  
Persistent Slip Bands ◽  
Relief Formation ◽  
Cyclic Slip

Two fatigued materials with f.c.c. lattice, i.e. pure polycrystalline copper and austenitic Sanicro 25 stainless steel, were subjected to the study of the persistent slip markings (PSMs) developed on the surface of the suitably oriented grains. They were observed using scanning electron microscopy (SEM) and thin surface FIB lamellae were prepared and studied by transmission electron microscopy (TEM). The aim was to correlate the specimen surface profile with the underlying internal dislocation structure. The localization of the intensive cyclic slip into persistent slip bands (PSBs) of the material was observed and associated with the PSMs on the specimen surface. Extrusions, intrusions and the dislocation structure appertaining to them were analysed, documented and discussed in relation to the models of fatigue crack initiation.

Specific features of relief formation on silicon etched by a focused ion beam

2010 ◽  
Vol 36 (11) ◽  
pp. 991-993 ◽  
Author(s):  
N. N. Gerasimenko ◽  
A. A. Chamov ◽  
N. A. Medetov ◽  
V. A. Khanin
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Relief Formation

Investigation of the Three-Dimensional Shape of Slip Bands in Fatigued Dual Phase Steel

2014 ◽  
Vol 891-892 ◽  
pp. 482-487
Author(s):  
Lisa Zellmer ◽  
Stanislav Tereschenko ◽  
Angelika Brueckner-Foit ◽  
Peter Lehmann
Keyword(s):  
White Light ◽  
Dual Phase Steel ◽  
Ion Beam ◽  
Fatigue Crack Initiation ◽  
Three Dimensional ◽  
Dual Phase ◽  
Slip Bands ◽  
True Shape ◽  
Dimensional Shape ◽  
Three Dimensional Shape

The formation and the three-dimensional shape of slip bands in a fatigued dual phase steel were analyzed with the purpose of understanding the relation between fatigue crack initiation and the topography development on the specimen surface. Fatigue tests with small dog-bone-shaped specimens were conducted under fully reversed axial loading (R = -1) with a constant stress amplitude and were interrupted when the first slip bands occurred and at defined numbers of load cycles, respectively. Subsequently the surface topography of the specimen was investigated with a white light interferometer with hundredfold magnification and high numerical aperture (NA = 0.9) which allows analyzing the surface of individual grains. The results were confirmed by additional atomic force microscopy measurements. Based on this analysis the height, width and length of the slip bands are known at different stages of the fatigue process. The results obtained using white light interferometry and AFM, were checked by cutting individual slip bands with the help of focused ion beam thus revealing the true shape of the slip bands.

Fate of Carbon During the Formation of Earth’s Core

2020 ◽  
Author(s):  
Ingrid Blanchard ◽  
Eleanor Jennings ◽  
Ian Franchi ◽  
Zuchao Zhao ◽  
Sylvain Petitgirard ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Early Stage ◽  
Ion Beam ◽  
Light Element ◽  
Major Elements ◽  
Core Formation ◽  
Crustal Rocks ◽  
The Earth ◽  
Diamond Anvil ◽  
Laser Heated

<p>Carbon is an element of great importance in the Earth, because it is intimately linked to the presence of life at the surface, and, as a light element, it may contribute to the density deficit of the Earth’s iron-rich core. Carbon is strongly siderophile at low pressures and temperatures (1), hence it should be stored mainly in the Earth’s core. Nevertheless, we still observe the existence of carbon at the surface, stored in crustal rocks, and in the mantle, as shown by the exhumation of diamonds. The presence of carbon in the crust and mantle could be the result of the arrival of carbon during late accretion, after the process of core formation ceased, or because of a change in its metal–silicate partitioning behavior at the conditions of core formation (P >40 GPa – T >3500 K). Previous studies reported metal–silicate partitioning of carbon based on experiments using large volume presses up to 8 GPa and 2200°C (2). Here, we performed laser-heated diamond anvil cell experiments in order to determine carbon partitioning between liquid metal and silicate at the extreme conditions of Earth’s core–mantle differentiation. We recovered our samples using the Focused Ion Beam technique and welded a 3 μm thick slice of each sample onto a TEM grid. Major elements were analyzed by electron microprobe, whereas the concentrations of carbon in the silicate were analyzed by nanoSIMS. We thus have obtained metal–silicate partitioning results for carbon at PT conditions relevant to planetary core formation, where C remains siderophile in all experiments, but partition coefficients are up to two orders of magnitude lower than in low PTexperiments. We derive a new parameterization of the pressure–temperature dependence of the metal–silicate partitioning of carbon and apply this in a state-of-the-art model of planet formation and differentiation (3,4) that is based on astrophysical N-body accretion simulations. Results show that BSE carbon concentrations increase strongly starting at a very early stage of Earth’s accretion and, depending on the concentration of carbon in accreting bodies, can easily reach or exceed estimated BSE values.</p><p> </p><p>(1) Dasgupta et al., 2013. Geochimica et Cosmochimica Acta 102, 191-212</p><p>(2) Li et al., 2016. Nature Geoscience 9, 781–785</p><p>(3) Rubie et al., 2015. Icarus 248, 89–108</p><p>(4) Rubie et al., 2016. Science 353, 1141–1144</p><p> </p>

Fatigue Crack Initiation in Crystalline Materials – Experimental Evidence and Models

2007 ◽  
Vol 345-346 ◽  
pp. 379-382 ◽  
Author(s):  
Jaroslav Polák ◽  
Jiří Man ◽  
Tomáš Vystavěl ◽  
Lukáš Zouhar
Keyword(s):  
Fatigue Crack ◽  
Cyclic Loading ◽  
Crack Initiation ◽  
Experimental Evidence ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Fatigue Crack Initiation ◽  
Three Dimensional ◽  
Crystalline Materials ◽  
316L Austenitic Stainless Steel

Recent observations relevant to the early stages of the fatigue damage of crystalline materials are reviewed. Experimental evidence on the localization of the cyclic plastic strain and on the surface relief formation in cyclic loading of 316L austenitic stainless steel is presented. The focused ion beam is used for exposing three-dimensional evidence of persistent slip markings (PSMs). PSMs consist of extrusions and parallel or alternating intrusions which develop during cyclic loading. Monte Carlo simulations of vacancy generation within persistent slip band (PSB) and their migration to the matrix where they annihilate on the edge dislocations are used to simulate the growth of extrusions and intrusions. The results of the simulations are compared with experimental data and discussed in terms vacancy models of fatigue crack initiation.

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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