Crystal structure of modulated martensite and crystallographic correlations between martensite variants of Ni50Mn38Sn12alloy

2016 ◽  
Vol 49 (4) ◽  
pp. 1276-1283 ◽  
Author(s):  
Chunqing Lin ◽  
Haile Yan ◽  
Yudong Zhang ◽  
Claude Esling ◽  
Xiang Zhao ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electron Backscatter Diffraction ◽  
Type I ◽  
Type Ii ◽  
Plate Interface ◽  
Modulated Structure ◽  
Austenite Grain ◽  
Twinning Plane ◽  
Backscatter Diffraction ◽  
Comprehensive Study

A comprehensive study on the crystal structure, the microstructure and the crystallographic features of the martensite in an Ni50Mn38Sn12alloy has been conducted in the present work. The results show that the martensite possesses a 4O modulated structure. The martensite is organized into broad plates in the original austenite grain. The plates contain irregularly shaped colonies with two characteristic microstructural patterns: a classical lamellar pattern and a herringbone pattern. Crystallographic analyses by scanning electron microscopy/electron backscatter diffraction demonstrate that in each colony there are four orientation variants (A, B, C and D) and they form three types of twins (type I, type II and compound twin). The interfaces between corresponding variants are coincident with their twinning planeK1. The interface planes of the compound twin pairs A&D and B&C can have one or two different orientations, which leads to the two microstructural patterns. The corresponding variants in neighboring colonies within one broad plate (intra-plate colonies) possess close orientations, but the type I and the type II twin relationships are interchanged. The variants in neighboring colonies situated in adjacent plates (inter-plate colonies) are type I or type II twin related but with some angular deviations. The plate interface is defined by the {221} plane of the variant pair with largest thickness. The results of the present work provide comprehensive microstructural and crystallographic information on modulated martensite in NiMnSn alloys that is useful for the understanding of their specific functionalities and helpful for further investigation on property optimization of these materials.

Crystal Structure and Microstructure of Martensite in Ni-Mn-In Alloys and the Behavior of Variant Rearrangement under Uniaxial Loading

2016 ◽  
Vol 879 ◽  
pp. 518-523
Author(s):  
Hai Le Yan ◽  
Yu Dong Zhang ◽  
Zon Bin Li ◽  
Claude Esling ◽  
Xiang Zhao ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Type I ◽  
Modulated Structure ◽  
Self Organized ◽  
Fundamental Information ◽  
Twinning Plane ◽  
Plate Shape ◽  
Schmid Factor ◽  
Underlying Mechanisms ◽  
Structure And Microstructure

In the present work, the crystal structure and microstructure of martensite in Ni-Mn-In alloys and the variant rearrangement behavior under the external mechanical loading were investigated. Results show that the martensite has an incommensurate 6M modulated structure (I2/m (α0γ)00) with the modulation wave vector q = 0.3437c*. Microstructure of martensite is in plate shape and self-organized with four orientation variants that are alternately distributed and related in either type-I, or type-II or compound twin relation. The variant interfaces are in coincidence with their corresponding twinning plane and then should be considered coherent. Under the uniaxial compression, the loading located in the common positive Schmid factor zone of the three types of detwinning systems might be favorable to obtain the single variant state. This study is expected to offer a fundamental information of crystal structure, microstructures and variant rearrangement behaviors in Ni-Mn-In alloys, so as to understand the underlying mechanisms of their multifunctional magneto-responsive properties.

Crystal structure and crystallographic characteristics of martensite in Ni50Mn38Sb12 alloys

2016 ◽  
Vol 49 (2) ◽  
pp. 513-519 ◽  
Author(s):  
Chunyang Zhang ◽  
Haile Yan ◽  
Yudong Zhang ◽  
Claude Esling ◽  
Xiang Zhao ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electron Backscatter Diffraction ◽  
Type I ◽  
X Ray Diffraction ◽  
Orientation Relationships ◽  
Fundamental Information ◽  
Orientation Variant ◽  
Crystallographic Characteristics ◽  
Backscatter Diffraction ◽  
Atomic Coordinates

For Ni–Mn–Sb ferromagnetic multifunctional alloys, the crystal structures of martensite variants and the orientation relationships between them are decisive factors for their magnetic field-induced behaviours and are hence of importance. Such information has rarely been reported in the literature. In the present work, the crystal structure, microstructure and orientation relationships of Ni–Mn–Sb martensite were thoroughly investigated by X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). Through XRD analyses, the crystal structure of the martensite, including the crystal system, the space group, the lattice parameters and the atomic coordinates, was fully resolved. The structure is orthorhombic and can be represented with a 4O superstructure. EBSD analyses show that the Ni–Mn–Sb martensite has a lamellar form. One martensite lamella corresponds to one orientation variant. The lamellae are organized in long plate-shaped colonies. Within each colony, four distinct orientation variants (A, B, C and D) appear repeatedly and extend in roughly the same direction. The four variants are twin related to one another, with variants A and C (or variants B and D) forming a type I twin, variants A and B (or C and D) a type II twin, and variants A and D (or B and C) a compound twin. The complete twinning elements for each twin relation were thus fully determined. The interfaces between the variants were identified to be their corresponding twinning planes. All these results provide fundamental information for Ni–Mn–Sb alloys that is useful for interpreting their magnetic and mechanical characteristics.

Calculation Methods to Determine Crystallographic Elements Based on Electron Diffraction Orientation Measurements by SEM/EBSD or TEM

2012 ◽  
Vol 706-709 ◽  
pp. 2674-2679
Author(s):  
Yu Dong Zhang ◽  
Zong Bin Li ◽  
Claude Esling ◽  
Xiang Zhao ◽  
Liang Zuo
Keyword(s):  
Crystal Structure ◽  
Electron Diffraction ◽  
Sample Surface ◽  
Type I ◽  
Type Ii ◽  
Calculation Methods ◽  
Orientation Relationships ◽  
Prepared Sample ◽  
Twinning Plane ◽  
Twinning Direction

In the present work, we summarized two calculation methods to determine some specific crystallographic elements based on electron diffraction orientation measurements by SEM/EBSD or TEM. The first one is to determine the twin type and twinning elements of crystal twins based on the minimum shear criterion, using the experimentally determined twinning plane for Type I twin and compound twin or twinning direction for Type II twin as initial input. The method is valid for any crystal structure. The second one is one to determine the plane indices of the faceted interfaces where the orientation relationships (ORs) between the adjacent crystals are reproducible. The method requires one prepared sample surface instead of two perpendicular surfaces. These methods are expected to facilitate the related microstructural characterizations.

Crystal structure of magnesium chromium vanadate Mg2CrV3O11, a member of the A2BV3O11 vanadate family

2007 ◽  
Vol 22 (3) ◽  
pp. 246-252 ◽  
Author(s):  
A. Worsztynowicz ◽  
S. M. Kaczmarek ◽  
W. Paszkowicz ◽  
R. Minikayev
Keyword(s):  
Crystal Structure ◽  
Rietveld Method ◽  
Ion Pairs ◽  
Exchange Constant ◽  
Type I ◽  
Type Ii ◽  
Paramagnetic Resonance ◽  
Interatomic Distances ◽  
Electron Paramagnetic ◽  
Full Occupancy

The crystal structure of recently discovered chromium (III) dimagnesium trivanadate (V) Mg2CrV3O11 was refined using the Rietveld method. The crystal system of Mg2CrV3O11 is triclinic with space group P1− (Mg1.7Zn0.3GaV3O11 type) and lattice parameters a=6.4057(1) Å, b=6.8111(1) Å, c=10.0640(2) Å, α=97.523(1)°, β=103.351(1)°, γ=101.750(1)°, and Z=2. The characteristic feature of compounds in the A2BV3O11 (A=Mg, Zn and B=Ga, Fe, Cr) family is a strong tendency to share the octahedral M(1) and M(2) sites by both divalent A and trivalent B atoms, and the bipyramidal M(3) sites occupied by divalent A ions. In the present refinement, the only constraint assuming full occupancy of the M(1), M(2), and M(3) sites leads to the following Cr/(Cr+Mg) ratios: 0.70(2) at M(1), 0.24(2) at M(2), and 0.03(2) at M(3). These occupancies are discussed and compared to those of isotypic compounds. The values of interatomic distances are found to be comparable with those reported by R. D. Shannon in 1976. Electron paramagnetic resonance has been also analyzed. Two absorption lines with g≈2.0 (type I) and g≈1.98 (type II) have been recorded in the EPR spectra, and attributed to V4+ ions and Cr3+–Cr3+ ion pairs, respectively. The exchange constant J between Cr3+ ions has been calculated.

scholarly journals Characterization of Coarse-Grained Heat-Affected Zones in Al and Ti-Deoxidized Offshore Steels

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1096
Author(s):  
Henri Tervo ◽  
Antti Kaijalainen ◽  
Vahid Javaheri ◽  
Satish Kolli ◽  
Tuomas Alatarvas ◽  
...  
Keyword(s):  
Prior Austenite ◽  
Electron Backscatter Diffraction ◽  
Coarse Grained ◽  
Grain Coarsening ◽  
Austenite Grain ◽  
The Matrix ◽  
Backscatter Diffraction ◽  
Prior Austenite Grain ◽  
Deoxidation Practice

Deterioration of the toughness in heat-affected zones (HAZs) due to the thermal cycles caused by welding is a known problem in offshore steels. Acicular ferrite (AF) in the HAZ is generally considered beneficial regarding the toughness. Three experimental steels were studied in order to find optimal conditions for the AF formation in the coarse-grained heat-affected zone (CGHAZ). One of the steels was Al-deoxidized, while the other two were Ti-deoxidized. The main focus was to distinguish whether the deoxidation practice affected the AF formation in the simulated CGHAZ. First, two different peak temperatures and prolonged annealing were used to study the prior austenite grain coarsening. Then, the effect of welding heat input was studied by applying three cooling times from 800 °C to 500 °C in a Gleeble thermomechanical simulator. The materials were characterized using electron microscopy, energy-dispersive X-ray spectrometry, and electron backscatter diffraction. The Mn depletion along the matrix-particle interface was modelled and measured. It was found that AF formed in the simulated CGHAZ of one of the Ti-deoxidized steels and its fraction increased with increasing cooling time. In this steel, the inclusions consisted mainly of small (1–4 μm) TiOx-MnS, and the tendency for prior austenite grain coarsening was the highest.

Effect of the Metallurgical State of Austenite on the Microtexture Properties of the Bainitic Transformation in a Low Alloy Steel

2011 ◽  
Vol 172-174 ◽  
pp. 772-777 ◽  
Author(s):  
Sophie Lubin ◽  
Anne Francoise Gourgues-Lorenzon ◽  
Brigitte Bacroix ◽  
Hélène Réglé ◽  
Frank Montheillet
Keyword(s):  
Electron Backscatter Diffraction ◽  
Lath Martensite ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Local Variant ◽  
Angle Pair ◽  
Selection For ◽  
Hot Torsion ◽  
Lower Temperature ◽  
Backscatter Diffraction

The effect of the metallurgical state of austenite (undeformed vs. deformed vs. deformed + recrystallised) on the properties of the austenite to bainite transformation were investigated thanks to thermal (Gleeble simulations) and thermomechanical (hot torsion) treatments. No obvious influence of the state of austenite was found, using electron backscatter diffraction, on the resulting microtexture. Advantages and drawbacks of using misorientation angle histograms vs. axis-angle pair distribution are discussed regarding investigations of local variant selection. For an austenite grain size higher than about 50 µm, a strong effect of the transformation temperature was evidenced, bainite formed at lower temperature (530°C) exhibiting a microtexture close to that of lath martensite in the same steel.

scholarly journals On the Formation of Micro-Shrinkage Porosities in Ductile Iron Cast Components

Metals ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 551 ◽  
Author(s):  
Ehsan Ghassemali ◽  
Anders Jarfors ◽  
Attila Diószegi
Keyword(s):  
Ductile Iron ◽  
Electron Backscatter Diffraction ◽  
Pressure Change ◽  
Grain Structure ◽  
Absolute Pressure ◽  
Dendrite Fragmentation ◽  
Austenite Grain ◽  
Backscatter Diffraction ◽  
Parent Austenite ◽  
Ebsd Method

A combination of direct austempering after solidification (DAAS) treatment and electron backscatter diffraction (EBSD) method was used to study the formation of micro-shrinkage porosities in ductile iron. Analyzing the aus-ferritic microstructure revealed that most of micro-shrinkage porosities are formed at the retained austenite grain boundaries. There was no obvious correlation between the ferrite grains or graphite nodules and micro-shrinkage porosities. Due to the absolute pressure change at the (purely) shrinkage porosities, the dendrite fragmentation rate during the DAAS process would be altered locally, which caused a relatively finer parent-austenite grain structure near such porosities.

Notizen: The Crystal Structure of N3P3C15(NPPh3) — a Novel Conformation in Phosphazenylcyclophosphazene Chemistry

1976 ◽  
Vol 31 (7) ◽  
pp. 999-1000 ◽  
Author(s):  
Y. Sudhakara Babu ◽  
T. Stanley Cameron ◽  
S. S. Krishnamurthy ◽  
H. Manohar ◽  
Robert A. Shaw
Keyword(s):  
Crystal Structure ◽  
Crystallographic Structure ◽  
Type I ◽  
Type Ii ◽  
Structure Investigation ◽  
X Ray ◽  
Ring Segment

An X-ray crystallographic structure investigation of pentachloro(triphenylphosphazenyl)cyclotriphosphazatriene, N3P3C15(NPPh3), reveals a novel conformation (type I) of the triphenylphosphazenyl group with respect to the adjacent ring segment. This is contrasted with the structure of gem. –N3P3CI4Ph(NPPh3), where a type II conformation is observed.

Influence of Crystallography on Nucleation of Ferrite Precipitates at Austenite Grain Boundary Corners in a Co-15Fe Alloy

2011 ◽  
Vol 172-174 ◽  
pp. 378-383
Author(s):  
Guo Hong Zhang ◽  
Tomoaki Takeuchi ◽  
Masato Enomoto ◽  
Yoshitaka Adachi
Keyword(s):  
Grain Boundary ◽  
Electron Backscatter Diffraction ◽  
Major Influence ◽  
Austenite Grain ◽  
Electron Backscatter ◽  
The Matrix ◽  
Triple Points ◽  
Individual Grains ◽  
Austenite Grain Boundary ◽  
Backscatter Diffraction

The nucleation of bcc ferrite precipitates at austenite grain corners in a Co-15Fe alloy was studied by serial sectioning coupled with electron backscatter diffraction (EBSD) analysis. Grain corners were identified by recombination of triple points and triangular annihilation, whereas quite a few precipitates were surrounded by more than four matrix grains when twins were counted as individual grains. More than 40% of corners composed all of high angle grain boundaries were vacant at an undercooling of ~60°C from the g/(a+g) phase boundary. All the precipitates had K-S or N-W orientation relationship with at least one grain and a larger proportion of them had the OR with two and three grains. For half of vacant corners a hypothetical precipitate could have the OR with more than one grain. It is likely that not only the misorientations among the matrix grains, but also the orientations of the grain boundary planes have a major influence on nucleation potency even at grain corners.

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