Orientation Imaging of A Nb-Ti-Si Directionally Solidified In-Situ Composite

1996 ◽  
Vol 54 ◽  
pp. 350-351
Author(s):  
J. A. Sutliff ◽  
B. P. Bewlay
Keyword(s):  
Dendritic Structure ◽  
Microstructural Characterization ◽  
Transverse Cross Section ◽  
Solidification Structure ◽  
Nominal Composition ◽  
Silicide Phase ◽  
Euler Angles ◽  
Directionally Solidified ◽  
Data Set ◽  
Gray Phase

In this paper we report on the microstructural characterization of a directionally solidified (DS) Nb-Ti-Si alloy. The solidified ingot had a nominal composition of Nb-33 at%Ti-16 at% Si and was grown using the Czochralski technique with growth rate of 5 mm/min. The as-solidified ingot was approximately 50 mm long with a 10 mm diameter. The microstructure was examined using backscatter electron imaging and the microtexture of each of the phases was determined using the Electron BackScattering Pattern (EBSP) technique for electron diffraction in the scanning electron microscope. The details of the experiments are similar to those we have reported previously. Automated EBSP scans were acquired in order to map the local texture (microtexture) over most of a transverse cross-section through the ingot.Figure 1 is a backscattered electron image (BEI) of a transverse section of the as-solidified microstructure. In this image, the bcc-Nb phase is the lighter gray phase and has a dendritic structure. The dark gray phase is (Nb,Ti)3Si having a Ti3P crystal structure. The silicide phase appears as both multiply-faceted dendrites and irregularly bounded grains. A pattern of shading, due to Ti segregation, can be seen in figure 1 and suggests a cellular solidification structure. Figure 2 is a BEI taken at higher magnification to show a region that was analyzed by automated-EBSP. Figure 3 contains orientation images generated from the automated-EBSP data set. In Figure 3a, the color black signifies positions for which no Nb diffraction patterns could be indexed and other shades of gray signify specific Nb orientations, as described by a set of Euler angles. A similarly generated orientation image for the silicide phase is shown in Figure 3b. The greyscale image presented here is actually a rendering of a truecolor image based on a RGB triplet using the Euler angles.

scholarly journals Impact of Solidification on Inclusion Morphology in ESR and PESR Remelted Martensitic Stainless Steel Ingots

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 408
Author(s):  
Ewa Sjöqvist Persson ◽  
Sofia Brorson ◽  
Alec Mitchell ◽  
Pär G. Jönsson
Keyword(s):  
Stainless Steel ◽  
Martensitic Stainless Steel ◽  
Dendritic Structure ◽  
Steel Grade ◽  
Solidification Structure ◽  
Production Scale ◽  
Steel Grades ◽  
Steel Ingots ◽  
Columnar Dendritic Structure ◽  
The Impact

This study focuses on the impact of solidification on the inclusion morphologies in different sizes of production-scale electro-slag remelting (ESR) and electro-slag remelting under a protected pressure-controlled atmosphere, (PESR), ingots, in a common martensitic stainless steel grade. The investigation has been carried out to increase the knowledge of the solidification and change in inclusion morphologies during ESR and PESR remelting. In order to optimize process routes for different steel grades, it is important to define the advantages of different processes. A comparison is made between an electrode, ESR, and PESR ingots with different production-scale ingot sizes, from 400 mm square to 1050 mm in diameter. The electrode and two of the smallest ingots are from the same electrode charge. The samples are taken from both the electrode, ingots, and rolled/forged material. The solidification structure, dendrite arm spacing, chemical analyzes, and inclusion number on ingots and/or forged/rolled material are studied. The results show that the larger the ingot and the further towards the center of the ingot, the larger inclusions are found. As long as an ingot solidifies with a columnar dendritic structure (DS), the increase in inclusion number and size with ingot diameter is approximately linear. However, at the ingot size (1050 mm in diameter in this study) when the center of the ingot converts to solidification in the equiaxial mode (EQ), the increase in number and size of the inclusions is much higher. The transition between a dendritic and an equiaxial solidification in the center of the ingots in this steel grade takes place in the region between the ingot diameters of 800 and 1050 mm.

Dependence of Microstructures and Mechanical Properties on the Growth Rate and Composition in Directionally Solidified Mg-Gd Alloys

2022 ◽  
Vol 327 ◽  
pp. 82-97
Author(s):  
He Qin ◽  
Guang Yu Yang ◽  
Shi Feng Luo ◽  
Tong Bai ◽  
Wan Qi Jie
Keyword(s):  
Mechanical Properties ◽  
Growth Rate ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Dendritic Structure ◽  
Directionally Solidified ◽  
Dendrite Morphology ◽  
Microstructural Parameters ◽  
Wide Range ◽  
Microstructures And Mechanical Properties

Microstructures and mechanical properties of directionally solidified Mg-xGd (5.21, 7.96 and 9.58 wt.%) alloys were investigated at a wide range of growth rates (V = 10-200 μm/s) under the constant temperature gradient (G = 30 K/mm). The results showed that when the growth rate was 10 μm/s, different interface morphologies were observed in three tested alloys: cellular morphology for Mg-5.21Gd alloy, a mixed morphology of cellular structure and dendritic structure for Mg-7.96Gd alloy and dendrite morphology for Mg-9.58Gd alloy, respectively. Upon further increasing the growth rate, only dendrite morphology was exhibited in all experimental alloys. The microstructural parameters (λ1, λ2) decreased with increasing the growth rate for all the experimental alloy, and the measured λ1 and λ2 values were in good agreement with Trivedi model and Kattamis-Flemings model, respectively. Vickers hardness and the ultimate tensile strength increased with the increase of the growth rate and Gd content, while the elongation decreased gradually. Furthermore, the relationships between the hardness, ultimate tensile strength, the growth rate and the microstructural parameters were discussed and compared with the previous experimental results.

scholarly journals Characterization and Corrosion Resistance Behavior of Shape Memory Stainless Steel Developed by Alternate Routes

Metals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 13
Author(s):  
David Dias ◽  
Sandra Nakamatsu ◽  
Carlos Alberto Della Rovere ◽  
Jorge Otubo ◽  
Neide Aparecida Mariano
Keyword(s):  
Corrosion Resistance ◽  
Shape Memory ◽  
Dendritic Structure ◽  
Microstructural Characterization ◽  
Rolling Process ◽  
Chloride Ions ◽  
Secondary Phases ◽  
Electrochemical Tests ◽  
The Matrix ◽  
Routing Methods

The microstructural characterization and corrosion resistance behavior of Fe-Mn-Si-Cr-Ni alloy with shape memory effect was studied under different mechanical processing conditions and heat treatments, which were produced using conventional casting and routing methods to reduce costs and make production viable. Microstructural characterization was performed with electron microscopy and x-ray diffraction techniques, electrochemical tests with polarization, and thermogravimetry techniques. The cast condition presented a dendritic structure and the presence of the secondary phases: ferrite-δ and Chi-X phase. The heat treatment eliminated phases, reincorporated elements in the matrix, and increased the austenitic grain. After the hot rolling process, the alloy exhibited a refined microstructure with recrystallized austenitic grains. The heat-treated condition presented better oxidation resistance than the other conditions, while the hot-rolled condition showed repassivation of the pits, raising them to higher levels. All conditions presented low corrosion resistance in environments containing chloride ions.

Microstructural Characterization of Pt/Ti and RuO2 Electrodes on SiO2/Si Annealed in the Oxygen Ambient

1996 ◽  
Vol 433 ◽  
Author(s):  
Jeong Soo Lee ◽  
Hyun JA Kwon ◽  
Young Woo Jeong ◽  
Hyun HA Kim ◽  
Kyu HO Park ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Film Surface ◽  
Microstructural Characterization ◽  
Silicide Phase ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Degree Of Oxidation ◽  
Thin Interlayer ◽  
Increasing Temperature

AbstractMicrostructures and interdiffusions of Pt/Ti/SiO2/Si and RuO2/SiO2/Si during annealing in O2 were investigated using x-ray diffraction, Auger electron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The degree of oxidation and the interdiffusion of elements have remarkably increased with increasing temperature above 500 °C for the Pt/Ti/SiO2/Si case. The generation of Pt hillocks commenced at 500 °C. The Pt-silicide phase was also observed near the TiOx/SiO2 interface. The microstructural variations occurred to only a small amount for the RuO2/SiO2/Si case over the temperature range 300 – 700 °C. While there was no hillock formation, the RuO2 film surface was roughened by the thermal grooving phenomenon. A thin interlayer phase was found at the RuO2/SiO2 interface.

Effect of Travelling Magnetic Fields on the Dendritic Microstructure of AlSi and AlSiMn

2013 ◽  
Vol 765 ◽  
pp. 235-240
Author(s):  
Andreas Orth ◽  
Lorenz Ratke
Keyword(s):  
Fluid Flow ◽  
Cross Sections ◽  
Mutual Influence ◽  
Dendritic Structure ◽  
Solidification Velocity ◽  
Directionally Solidified ◽  
Dendritic Microstructure ◽  
Two Factors ◽  
Traveling Magnetic Field ◽  
Particle Pushing

The microstructure formation of AlSi alloys is known to be sensitive to specific solidification conditions. In particular, small fractions of heavier alloying atoms can lead to the precipitation of intermetallic phases. Moreover, the mainly dendritic structure is also sensitive to fluid flow in the melt. These two factors and their mutual influence is examined in this paper. The solidification of AlSi7 and AlSi7Mn1 samples was studied while inducing fluid flow by a traveling magnetic field (TMF) of approximately 5 mT strength, traveling up or down the sample axis. All samples were molten and directionally solidified at constant solidification velocities between 0.03 and 0.24 mm/s. The application of two separate heaters allowed the fixation of constant temperature gradients in the solid and liquid parts of the samples, the use of a transparent silica aerogel crucible permitted optical verification of the solidification velocity. Cross sections were cut from the processed samples and the microstructure analyzed using light microscopy and SEM-EDX. From these images, values for the primary, secondary and tertiary dendrite arm spacing were retrieved. Results are presented which show a clear effect of the TMF-induced fluid flow on the binary samples, but almost none for the ternary alloy. Finally, an explanation proposing a process of precipitate particle pushing is given.

Effect of Electromagnetic Field on the Solidification Structure of HMn084 Brass

2011 ◽  
Vol 201-203 ◽  
pp. 2904-2908
Author(s):  
Bao Mian Li ◽  
Hai Tao Zhang ◽  
Jian Zhong Cui
Keyword(s):  
Electromagnetic Field ◽  
Uniform Distribution ◽  
Phase Changes ◽  
Solidification Structure ◽  
Current Intensity ◽  
Silicide Phase ◽  
Cast Structure ◽  
Β Phase ◽  
Α Phase

The effect of electromagnetic field on the solidification structure of HMn084 brass (Cu-20%Zn-7.5%Mn-5.5%Al-1.5%Si-1%Fe-0.5%Pb in mass%) had been investigated in this paper. The results show that the as-cast structure of HMn084 brass is composed of matrix β-phase, small amount of α-phase and silicide (Mn, Fe)5Si3. Applying electromagnetic field during the solidification of HMn084 brass can refine grain and silicide phase, promote the uniform distribution of silicide phase. The morphology of silicide phase changes from coarse acicular and massive shape to fine acicular and massive shape. The above-mentioned effects become more obvious with the increasing in current intensity.

Microscopic study of the room temperature deformation mechanisms in β+γ' – (70 at.% Ni −30 at.% Al) in situ composite

1992 ◽  
Vol 50 (1) ◽  
pp. 912-913
Author(s):  
A. Misra ◽  
R. Gibala
Keyword(s):  
Microscopic Study ◽  
Room Temperature ◽  
Temperature Deformation ◽  
Nominal Composition ◽  
Second Phase ◽  
Directionally Solidified ◽  
Ductile Phase ◽  
Two Phase ◽  
Room Temperature Ductility

Ductile phase reinforcement is an attractive approach for enhancing the room temperature ductility and toughness of brittle intermetallics such as β−NiAl. For example, a directionally solidified alloy of nominal composition 70 at.% Ni −30 at.% Al, having a two-phase β (brittle matrix) and γ (ductile second phase) microstructure, exhibits up to 9% tensile ductility at room temperature [1]. In the present investigation, a microscopic study has been made to understand the mechanisms involved in the ductility enhancement of the β + γ composite.

Microstructure and microtexture of a Nb-16%Si (DS) Alloy

1995 ◽  
Vol 53 ◽  
pp. 122-123
Author(s):  
J. A. Sutliff ◽  
B. P. Bewlay
Keyword(s):  
High Temperature ◽  
Directional Solidification ◽  
Room Temperature ◽  
Microstructural Characterization ◽  
Crystallographic Analysis ◽  
Directionally Solidified ◽  
Heat Treated ◽  
Other Orientation

In-situ composite Nb-Si alloys have been studied by several investigators as potential high temperature structural materials. The two major processing routes used to fabricate these composites are directional solidification and extrusion of arc-cast solidified ingots. In both cases a stable microstructure of primary Nb dendrites in a eutectoid of Nb and Nb5Si3 phases is developed after heat treatment. The Nb5Si3 phase is stable at room temperature and forms as a decomposition product of the high temperature Nb3Si phase. The anisotropic microstructures developed by both directional solidification and extrusion require evaluation of the texture to fully interpret the fracture and other orientation dependent mechanical behavior of these composites.In this paper we report on the microstructural characterization of a directionally solidified (DS) and heat treated Nb-16 at.%Si alloy. The microtexture of each of the phases (Nb, Nb5Si3) was determined using the Electron BackScattering Pattern (EBSP) technique for electron diffraction in the scanning electron microscope. A system employing automatic diffraction pattern recognition, crystallographic analysis, and sample or beam scanning was used to acquire the microtexture data.

Slip Transfer Across Interphase Boundaries in Directionally Solidified β+(γ+γ') Ni-Fe-Al Alloys

1991 ◽  
Vol 238 ◽  
Author(s):  
A. Misra ◽  
R. Gibala
Keyword(s):  
Room Temperature ◽  
Tensile Elongation ◽  
Nominal Composition ◽  
Directionally Solidified ◽  
Β Phase ◽  
Slip Transfer ◽  
Temperature Observation ◽  
Interphase Boundaries ◽  
Slip Traces ◽  
Two Phases

ABSTRACTThe low ductility and toughness of β-NiAl alloys near room temperature pose major problems in their potential application as structural materials. The inability of the material to generate and move a sufficient density of dislocations at applied stresses below the fracture stress is the major cause for this inherent brittleness. A directionally solidified β+(γ+γ') composite of nominal composition Ni50Fe30Al20 (at.%) has been used to investigate the effect of interphase boundaries on the mechanical behavior of β phase. The composite exhibits 10% tensile elongation to fracture at room temperature. Observation of slip traces and dislocation substructures shows that the normally brittle β phase undergoes extensive plastic deformation afforded by slip transfer from the plastically soft (γ+γ') phase mixture across the semi-coherent β/(γ+γ') interface. The effect of the orientation relationship between the two phases and the interface strength on the transfer of slip across the interphase boundary is discussed.

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