scholarly journals Multiple Influences of Molybdenum on the Precipitation Process in a Martensitic PH Stainless Steel

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1118
Author(s):  
Mattias Thuvander ◽  
Marcus Andersson ◽  
Krystyna Stiller
Keyword(s):  
Electron Microscopy ◽  
Stainless Steel ◽  
Atom Probe Tomography ◽  
Precipitation Hardening ◽  
Atom Probe ◽  
Precipitation Process ◽  
Transmission Electron ◽  
Initial Stage ◽  
The Matrix ◽  
Mo Content

Molybdenum has been found to influence the complex precipitation process in a martensitic precipitation hardening stainless steel during aging at 475 °C in several different ways. Three steels with different Mo content (0, 1.2 and 2.3 at.%) were investigated. Studies of the microstructure were performed with atom probe tomography and energy filtered transmission electron microscopy. It is shown that, at the initial stage of aging, a faster nucleation of Cu-rich clusters takes place with increasing Mo content. The Cu-clusters act as precipitation sites for other solute elements and promote the nucleation of Ni-rich phases. During further aging, a higher Mo content in the material instead slows down the growth and coarsening of the Ni-rich phases, because Mo segregates to the interface between precipitate and matrix. Additionally, Mo promotes decomposition of the matrix into α and α′ regions. After longer aging times (>40 h) quasicrystalline Mo-rich R′ phase forms (to a greater extent in the material having the highest Mo content). The observations serve to understand the hardness evolution during aging.

scholarly journals Characterization of Precipitation in Al-Li Alloy AA2195 by means of Atom Probe Tomography and Transmission Electron Microscopy

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Muna Khushaim ◽  
Torben Boll ◽  
Judith Seibert ◽  
Ferdinand Haider ◽  
Talaat Al-Kassab
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atom Probe Tomography ◽  
Stoichiometric Composition ◽  
Equilibrium Composition ◽  
Atom Probe ◽  
Chemical Mapping ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
The Matrix

The microstructure of the commercial alloy AA2195 was investigated on the nanoscale after conducting T8 tempering. This particular thermomechanical treatment of the specimen resulted in the formation of platelet-shapedT1Al2CuLi/θ′Al2Cuprecipitates within the Al matrix. The electrochemically prepared samples were analyzed by scanning transmission electron microscopy and atom probe tomography for chemical mapping. Theθ′platelets, which are less than 2 nm thick, have the stoichiometric composition consistent with the expected Al2Cu equilibrium composition. Additionally, the Li distribution inside theθ′platelets was found to equal the same value as in the matrix. The equally thinT1platelet deviates from the formula (Al2CuLi) in its stoichiometry and shows Mg enrichment inside the platelet without any indication of a higher segregation level at the precipitate/matrix interface. The deviation from the (Al2CuLi) stoichiometry cannot be simply interpreted as a consequence of artifacts when measuring the Cu and Li concentrations inside theT1platelet. The results show rather a strong hint for a true lower Li and Cu contents, hence supporting reasonably the hypothesis that the real chemical composition for the thinT1platelet in the T8 tempering condition differs from the equilibrium composition of the thermodynamic stable bulk phase.

Atomic-scale structural and compositional analyses of Ruddlesden-Popper planar faults in AO-excess SrTiO3 (A = Sr2+, Ca2+, Ba2+) ceramics

2009 ◽  
Vol 24 (8) ◽  
pp. 2596-2604 ◽  
Author(s):  
Sašo Šturm ◽  
Makoto Shiojiri ◽  
Miran Čeh
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dark Field ◽  
Atomic Scale ◽  
Transmission Electron ◽  
Initial Stage ◽  
Final Microstructure ◽  
Scanning Transmission ◽  
The Matrix ◽  
Annular Dark Field

The microstructure in AO-excess SrTiO3 (A = Sr2+, Ca2+, Ba2+) ceramics is strongly affected by the formation of Ruddlesden-Popper fault–rich (RP fault) lamellae, which are coherently intergrown with the matrix of the perovskite grains. We studied the structure and chemistry of RP faults by applying quantitative high-resolution transmission electron microscopy and high-angle annular dark-field scanning transmission electron microscopy analyses. We showed that the Sr2+ and Ca2+ dopant ions form RP faults during the initial stage of sintering. The final microstructure showed preferentially grown RP fault lamellae embedded in the central part of the anisotropic perovskite grains. In contrast, the dopant Ba2+ ions preferably substituted for Sr2+ in the SrTiO3 matrix by forming a BaxSr1−xTiO3 solid solution. The surplus of Sr2+ ions was compensated structurally in the later stages of sintering by the formation of SrO-rich RP faults. The resulting microstructure showed RP fault lamellae located at the surface of equiaxed BaxSr1-xTiO3 perovskite grains.

Origins of meteoritic nanodiamonds investigated by coordinated atom‐probe tomography and transmission electron microscopy studies

2019 ◽  
Vol 55 (6) ◽  
pp. 1382-1403 ◽  
Author(s):  
Josiah B. Lewis ◽  
Christine Floss ◽  
Dieter Isheim ◽  
Tyrone L. Daulton ◽  
David N. Seidman ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atom Probe Tomography ◽  
Atom Probe ◽  
Transmission Electron

scholarly journals Dopant Distribution in Atomic Layer Deposited ZnO:Al Films Visualized by Transmission Electron Microscopy and Atom Probe Tomography

2018 ◽  
Vol 30 (4) ◽  
pp. 1209-1217 ◽  
Author(s):  
Yizhi Wu ◽  
A. Devin Giddings ◽  
Marcel A. Verheijen ◽  
Bart Macco ◽  
Ty J. Prosa ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atom Probe Tomography ◽  
Atomic Layer ◽  
Atom Probe ◽  
Dopant Distribution ◽  
Transmission Electron
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