scholarly journals Crystallography of Fe–Mn–Al–Ni Shape Memory Alloys

2021 ◽  
Author(s):  
A. Leineweber ◽  
A. Walnsch ◽  
P. Fischer ◽  
H. Schumann
Keyword(s):  
Experimental Data ◽  
Hough Transform ◽  
Alloy Composition ◽  
Electron Backscatter Diffraction ◽  
Phenomenological Theory ◽  
Cubic Symmetry ◽  
Ni Alloys ◽  
Electron Backscatter ◽  
Backscatter Diffraction ◽  
Habit Planes

AbstractThe microstructure of the martensite formed in Fe–Mn–Al–Ni alloys of varying composition, consisting of A2 austenite and A1-like martensite, was investigated by means of electron backscatter diffraction (EBSD). While sufficiently structured EBSD patterns clearly revealed a tetragonal distortion of the (twinned) martensite, robust indexing using Hough-transform-based methods were successful only by assuming a cubic symmetry of the martensite. It was shown that predictions made based on the Phenomenological Theory of Martensite Crystallography (PTMC) were well compatible with the experimental data, irrespective of the alloy composition. This includes a (near-)Pitsch orientation relationship and habit planes close to {110}A2.

Analysis and characterization by electron backscatter diffraction of microstructural evolution in the adiabatic shear bands in Fe–Cr–Ni alloys

2009 ◽  
Vol 24 (8) ◽  
pp. 2617-2627 ◽  
Author(s):  
Huajie Yang ◽  
Yongbo Xu ◽  
Yasuaki Seki ◽  
Vitali F. Nesterenko ◽  
Marc André Meyers
Keyword(s):  
Microstructural Evolution ◽  
Electron Backscatter Diffraction ◽  
Shear Bands ◽  
Adiabatic Shear ◽  
Adiabatic Shear Bands ◽  
Localized Deformation ◽  
Ni Alloys ◽  
Electron Backscatter ◽  
Backscatter Diffraction ◽  
Equiaxed Grains

The microstructural evolution inside adiabatic shear bands in Fe–Cr–Ni alloys dynamically deformed (strain rates > 104 s−1) by the collapse of an explosively driven, thick-walled cylinder under prescribed strain conditions was examined by electron backscatter diffraction. The observed structure within the bands consisted of both equiaxed and elongated grains with a size of ∼200 nm. These fine microstructures can be attributed to recrystallization; it is proposed that the elongated grains may be developed simultaneously with localized deformation (dynamic recrystallization), and the equiaxed grains may be formed subsequently to deformation (static recrystallization). These recrystallized structures can be explained by a rotational recrystallization mechanism.

Angular Precision of Automated Electron Backscatter Diffraction Measurements

2011 ◽  
Vol 702-703 ◽  
pp. 548-553 ◽  
Author(s):  
Stuart I. Wright ◽  
Jay A. Basinger ◽  
Matthew M. Nowell
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Hough Transform ◽  
Angular Resolution ◽  
Electron Backscatter Diffraction ◽  
Electron Backscatter ◽  
Individual Grains ◽  
Backscatter Diffraction ◽  
Work First ◽  
Scanning Electron

Electron backscatter diffraction (EBSD) has become the preferred technique for characterizing the crystallographic orientation of individual grains in polycrystalline microstructures due to its ability to rapidly measure orientations at specific points in the microstructure at resolutions of approximately 20-50nm depending on the capabilities of the scanning electron microscope (SEM) and on the material being characterized. Various authors have studied the angular resolution of the orientations measured using automated EBSD. These studies have stated values ranging from approximately 0.1° to 2° [1-6]. Various factors influence the angular resolution achievable. The two primary factors are the accuracy of the detection of the bands in the EBSD patterns and the accuracy of the pattern center (PC) calibration. The band detection is commonly done using the Hough transform. The effect of varying the Hough transform parameters in order to optimize speed has been explored in a previous work [6]. The present work builds upon the earlier work but with the focus towards achieving the best angular resolution possible regardless of speed. This work first details the methodology used to characterize the angular precision then reports on various approaches to optimizing parameters to improve precision.

scholarly journals Crystallography of γ′-Fe4N formation in single-crystalline α-Fe whiskers

2020 ◽  
Vol 53 (4) ◽  
pp. 865-879
Author(s):  
Helge Schumann ◽  
Gunther Richter ◽  
Andreas Leineweber
Keyword(s):  
Orientation Relationship ◽  
Electron Backscatter Diffraction ◽  
Phenomenological Theory ◽  
Mechanical Constraints ◽  
Gaseous Nitriding ◽  
Iron Whiskers ◽  
Backscatter Diffraction ◽  
Fatigue Endurance ◽  
Habit Planes ◽  
Shear System

Gaseous nitriding of steel and iron can significantly improve their properties, for example corrosion resistance, fatigue endurance and tribological properties. In order to obtain a better understanding of the early stages of formation of the initial cubic primitive γ′-Fe4N, the mechanism and crystallography of the α–γ′ phase transformation was investigated under simplified conditions. Single-crystal α-Fe whiskers were nitrided at 823 K and a nitriding potential of 0.7 atm−1/2 for 20 min. The resulting microstructure and phases, as well as the crystallographic orientation of crystallites belonging to a particular phase, were characterized by scanning electron microscopy coupled with electron backscatter diffraction. The habit planes were investigated by single- and two-surface trace analysis. The α-Fe whiskers partly transform into γ′-Fe4N, where γ′ grows mainly in a plate-like morphology. An orientation relationship close to the rational Pitsch orientation relationship and {0.078 0.432 0.898}α and {0.391 0.367 0.844}γ′ as habit planes were predicted by the phenomenological theory of martensite crystallography (PTMC), adopting a {101}α〈101〉α shear system for lattice invariant strain, which corresponds to a {1 1 1}γ′〈1 12〉γ′ shear system in γ′. The encountered orientation relationship and the habit planes exhibit excellent agreement with predictions from the PTMC, although the transformation definitely requires diffusion. The γ′ plates mainly exhibit one single internally untwinned variant. The formation of additional variants due to strain accommodation, as well as the formation of a complex microstructure, was suppressed to a considerable extent by the fewer mechanical constraints imposed on the transforming regions within the iron whiskers as compared to the situation at the surface of bulk samples.

The Influence of Pre-Annealing on Recrystallization in Heavily Cold-Rolled Nickel

2007 ◽  
Vol 353-358 ◽  
pp. 703-706 ◽  
Author(s):  
Zhan Cheng ◽  
Andrew Godfrey ◽  
Yu Bin Zhang ◽  
Wei Liu ◽  
Qing Liu
Keyword(s):  
Experimental Data ◽  
Electron Backscatter Diffraction ◽  
Annealing Treatment ◽  
Longitudinal Section ◽  
Polycrystalline Nickel ◽  
Final Annealing ◽  
Cube Orientation ◽  
Electron Backscatter ◽  
Cold Rolled ◽  
Backscatter Diffraction

Polycrystalline nickel (99.999% purity) cold-rolled to a reduction of 96% has been given a two-step annealing treatment consisting of a pre-annealing at 180 °C or 220 °C for 2 hours, followed by a final annealing at 300 °C for 10 minutes. The changes in microstructure and texture during annealing have been followed using electron backscatter diffraction orientation measurements taken on the longitudinal section of the samples. The results suggest that pre-annealing at low temperature can enhance the formation recrystallized grains of cube orientation. Based on an analysis of the experimental data, possible reasons for the enhancement as a result of pre-annealing in the formation of cube orientation grains are discussed.

Orientation dependence of the martensite transformation in a quenched and partitioned steel subjected to uniaxial tension

2014 ◽  
Vol 47 (4) ◽  
pp. 1261-1266 ◽  
Author(s):  
D. De Knijf ◽  
T. Nguyen-Minh ◽  
R. H. Petrov ◽  
L. A. I. Kestens ◽  
John J. Jonas
Keyword(s):  
Martensite Transformation ◽  
Electron Backscatter Diffraction ◽  
Phenomenological Theory ◽  
Tensile Tests ◽  
Orientation Dependence ◽  
Uniaxial Tensile ◽  
Close Match ◽  
Uniaxial Tensile Testing ◽  
Electron Backscatter ◽  
Backscatter Diffraction

The orientation dependence of the austenite-to-martensite transformation during uniaxial tensile testing was modelled using the phenomenological theory of martensite crystallography and the mechanical driving force. It was validated experimentally by means of electron backscatter diffraction measurements on a pre-defined zone of a quenched and partitioned steel during interrupted tensile tests. A close match is obtained between the predictions of the model and the experimental observations.

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.

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