scholarly journals Boom boom pow: Shock-facilitated aqueous alteration and evidence for two shock events in the Martian nakhlite meteorites

2019 ◽  
Vol 5 (9) ◽  
pp. eaaw5549 ◽  
Author(s):  
L. Daly ◽  
M. R. Lee ◽  
S. Piazolo ◽  
S. Griffin ◽  
M. Bazargan ◽  
...  
Keyword(s):  
Electron Backscatter Diffraction ◽  
Mechanical Twinning ◽  
Igneous Rocks ◽  
Aqueous Alteration ◽  
Rock Interaction ◽  
Spatially Correlated ◽  
Electron Backscatter ◽  
Parent Rocks ◽  
Backscatter Diffraction ◽  
Water Rock Interaction

Nakhlite meteorites are ~1.4 to 1.3 Ga old igneous rocks, aqueously altered on Mars ~630 Ma ago. We test the theory that water-rock interaction was impact driven. Electron backscatter diffraction demonstrates that the meteorites Miller Range 03346 and Lafayette were heterogeneously deformed, leading to localized regions of brecciation, plastic deformation, and mechanical twinning of augite. Numerical modeling shows that the pattern of deformation is consistent with shock-generated compressive and tensile stresses. Mesostasis within shocked areas was aqueously altered to phyllosilicates, carbonates, and oxides, suggesting a genetic link between the two processes. We propose that an impact ~630 Ma ago simultaneously deformed the nakhlite parent rocks and generated liquid water by melting of permafrost. Ensuing water-rock interaction focused on shocked mesostasis with a high density of reactive sites. The nakhlite source location must have two spatially correlated craters, one ~630 Ma old and another, ejecting the meteorites, ~11 Ma ago.

scholarly journals To sink, swim, twin, or nucleate: A critical appraisal of crystal aggregation processes

Geology ◽  
2019 ◽  
Vol 47 (10) ◽  
pp. 948-952 ◽  
Author(s):  
Penny E. Wieser ◽  
Zoja Vukmanovic ◽  
Rüdiger Kilian ◽  
Emilie Ringe ◽  
Marian B. Holness ◽  
...  
Keyword(s):  
Dendritic Growth ◽  
Critical Appraisal ◽  
Bushveld Complex ◽  
Electron Backscatter Diffraction ◽  
Relative Orientation ◽  
Igneous Rocks ◽  
Growth Processes ◽  
Aggregation Processes ◽  
Electron Backscatter ◽  
Backscatter Diffraction

Abstract Crystal aggregates in igneous rocks have been variously ascribed to growth processes (e.g., twinning, heterogeneous nucleation, epitaxial growth, dendritic growth), or dynamical processes (e.g., synneusis, accumulation during settling). We tested these hypotheses by quantifying the relative orientation of adjacent crystals using electron backscatter diffraction. Both olivine aggregates from Kīlauea volcano (Hawaiʻi, USA) and chromite aggregates from the Bushveld Complex (South Africa) show diverse attachment geometries inconsistent with growth processes. Near-random attachments in chromite aggregates are consistent with accumulation by settling of individual crystals. Attachment geometries and prominent geochemical differences across grain boundaries in olivine aggregates are indicative of synneusis.

Cross Section Analysis of Cu Filled TSVs Based on High Throughput Plasma-FIB Milling

2012 ◽  
Author(s):  
Frank Altmann ◽  
Jens Beyersdorfer ◽  
Jan Schischka ◽  
Michael Krause ◽  
German Franz ◽  
...  
Keyword(s):  
High Resolution ◽  
Cross Section ◽  
High Throughput ◽  
Cross Sections ◽  
Electron Backscatter Diffraction ◽  
Grain Structure ◽  
Electron Backscatter ◽  
Section Surface ◽  
Backscatter Diffraction ◽  
Section Analysis

Abstract In this paper the new Vion™ Plasma-FIB system, developed by FEI, is evaluated for cross sectioning of Cu filled Through Silicon Via (TSV) interconnects. The aim of the study presented in this paper is to evaluate and optimise different Plasma-FIB (P-FIB) milling strategies in terms of performance and cross section surface quality. The sufficient preservation of microstructures within cross sections is crucial for subsequent Electron Backscatter Diffraction (EBSD) grain structure analyses and a high resolution interface characterisation by TEM.

scholarly journals Analysis of Strain Partitioning in Intercritically Deformed Microstructures via Interrupted Tensile Tests

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 112
Author(s):  
Unai Mayo ◽  
Nerea Isasti ◽  
José M. Rodríguez-Ibabe ◽  
Pello Uranga
Keyword(s):  
Electron Backscatter Diffraction ◽  
Tensile Tests ◽  
Correlation Technique ◽  
Strain Partitioning ◽  
High Angle ◽  
Electron Backscatter ◽  
Different Types ◽  
Final Deformation ◽  
Micro Alloyed Steel ◽  
Backscatter Diffraction

Intercritically deformed steels present combinations of different types of ferrite, such as deformed ferrite (DF) and non-deformed ferrite (NDF) grains, which are transformed during the final deformation passes and final cooling step. Recently, a grain identification and correlation technique based on EBSD has been employed together with a discretization methodology, enabling a distinction to be drawn between different ferrite populations (NDF and DF grains). This paper presents a combination of interrupted tensile tests with crystallographic characterization performed by means of Electron Backscatter Diffraction (EBSD), by analyzing the evolution of an intercritically deformed micro-alloyed steel. In addition to this, and using the nanoindentation technique, both ferrite families were characterized micromechanically and the nanohardness was quantified for each population. NDF grains are softer than DF ones, which is related to the presence of a lower fraction of low-angle grain boundaries. The interrupted tensile tests show the different behavior of low- and high-angle grain boundary evolution as well as the strain partitioning in each ferrite family. NDF population accommodates most of the deformation at initial strain intervals, since strain reaches 10%. For higher strains, NDF and DF grains behave similarly to the strain applied.

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