Early Stages of Recrystallization in ECAP-Deformed AA1050 Alloy Investigated by SEM Orientation Mapping

2013 ◽  
Vol 753 ◽  
pp. 267-270 ◽  
Author(s):  
Jagoda Poplewska ◽  
Henryk Paul ◽  
Katarzyna Berent
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Angle ◽  
Early Stages ◽  
Angular Pressing ◽  
Orientation Mapping ◽  
Purity Aluminium ◽  
Continuous Recrystallization ◽  
Equiaxed Grains ◽  
Scanning Electron

Early stages of recrystallization were observed for the technical purity aluminium alloy (AA1050). The samples were severely deformed by equal channel angular pressing and then annealed to obtain the state of partial recrystallization. The nucleation of new grains and the changes in ‘density’ of low- and high- angle boundaries were analysed using scanning electron microscopy equipped with high resolution EBSD system. After deformation in six passes along route A the alloy contained a structure of flat grains. On annealing, the structure coarsened and got transformed into nearly equiaxed grains by both discontinuous and continuous recrystallization. A particular role in the rise of nuclei and the structure spheroidization is attributed to migration of low-angle boundaries.

Substructure and Crystallography of Degenerate Pearlite in an Fe-C Binary Alloy

2007 ◽  
Vol 539-543 ◽  
pp. 4832-4837 ◽  
Author(s):  
Tadashi Furuhara ◽  
Tomokazu Moritani ◽  
K. Sakamoto ◽  
Tadashi Maki
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Growth Front ◽  
Isothermal Transformation ◽  
High Angle ◽  
Austenite Grain ◽  
Transmission Electron ◽  
Proeutectoid Ferrite ◽  
Lamellar Pearlite ◽  
Scanning Electron

Microstructures formed by degenerate pearlite transformation in an Fe-0.38mass%C alloy were studied by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Degenerate pearlite which contains fine cementite particles even at the growth front was observed with other structures such as proeutectoid ferrite, lamellar pearlite and bainite in a temperature range between 773K and 923K. As the isothermal transformation temperature is lowered, a fraction of the degenerate pearlite increases. The degenerate pearlite consists of ‘block’ (a region in which ferrite orientations are nearly the same) and ‘colony’ (a region containing cementite particles of nearly the same orientation), both of which are similar to those in lamellar pearlite. Block boundaries within an austenite grain are generally of high-angle type and their misorientations deviate largely from intervariant relationships for the K-S orientation relationship. In contrast, colony boundaries are of low-angle type. Cementite films are formed along those ferrite boundaries in the degenerate pearlite, presumably formed by encounter of the blocks or colonies.

Developmental morphology of the flower of Anthurium jenmanii: a new element in our understanding of basal Araceae

Botany ◽  
2008 ◽  
Vol 86 (1) ◽  
pp. 45-52 ◽  
Author(s):  
Denis Barabé ◽  
Christian Lacroix
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Calcium Oxalate ◽  
Floral Development ◽  
Developmental Morphology ◽  
Calcium Oxalate Crystals ◽  
Stages Of Development ◽  
Early Stages ◽  
Floral Primordia ◽  
Scanning Electron

The early stages of development of the inflorescence of Anthurium jenmanii Engl. were examined using scanning electron microscopy. The inflorescence of A. jenmanii consists of more than 100 flowers arranged in recognizable spirals. Each flower has four broad tepals enclosing four stamens that are not visible prior to anthesis. The gynoecium consists of two carpels. The floral primordia are first initiated on the lower portion of the inflorescence, they then increase in size and appear as transversely extended bulges. The two lateral tepals are the first organs to be initiated, followed shortly thereafter by the two median tepals. The two lateral stamens are initiated first, directly opposite the lateral tepals, and are followed by two median stamens initiated directly opposite the median tepals. A two-lobed stigma is clearly visible during the early stages of development of the gynoecium. On some of the young inflorescences, all floral parts were covered by extracellular calcium oxalate crystals. The release of these prismatic crystals occurs before the stamens and petals have reached maturity. The mode of floral development observed in Anthurium has similarities with that reported for Gymnostachys . However, contrary to Gymnostachys, the development of the flower of A. jenmanii is not unidirectional.

Plastic Deformation and Surface Recrystallization of Cu-4 Mass%Zn Alloy under Instantaneous Extrusion and High Speed Friction

2011 ◽  
Vol 467-469 ◽  
pp. 1280-1284
Author(s):  
Jun Hui Yin ◽  
Jian Zheng ◽  
Chang Zhi Jia ◽  
Ming Hui Ye
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Plastic Deformation ◽  
Surface Layer ◽  
High Speed ◽  
Fibrous Tissue ◽  
Equiaxed Grains ◽  
Rotating Band ◽  
Zn Alloy ◽  
Scanning Electron

As a special hot-work progress, artillery shooting test was put in practice, and rotating band specimen of Cu-4 Mass%Zn alloy was prepared. The mesostructure and microstructure evolution of the alloy under instantaneous extrusion and high speed friction were observed by optical microscopy (OM) and scanning electron microscopy (SEM). Severe plastic deformation (SPD) and dynamic recrystallization phenomena were researched. The analysis results are as follows. At the beginning of SPD, under the instantaneous compression, the surface layer of alloy became fibrous tissue with the phenomena of work-hardening. With the plastic deformation continue, temperature of alloy arising rapidly under the high speed friction. Recrystallization occurs within the outermost part of fibrous tissue due to heating, so subgrains gradually become homogeneous equiaxed grains. In addition, SPD has little effect on the inner tissue, which is full of equiaxed grains still. Between equiaxed grains and fibrous tissue, there are many oblique strip grains which formed by radial extrusion stress , tangential slip stress and axial sliding stress .

scholarly journals Architectural Development of Inflorescence in Hydrangea macrophylla cv. Hermann Dienemann

HortScience ◽  
2008 ◽  
Vol 43 (2) ◽  
pp. 361-365 ◽  
Author(s):  
Gilles Galopin ◽  
Sandrine Codarin ◽  
Jean-Daniel Viemont ◽  
Philippe Morel
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Inflorescence Development ◽  
Schematic Representation ◽  
Early Stages ◽  
Hydrangea Macrophylla ◽  
Floral Differentiation ◽  
Architectural Development ◽  
Scanning Electron

Architectural development of inflorescence in Hydrangea macrophylla cv. Hermann Dienemann was observed using scanning electron microscopy. The study of inflorescence morphogenesis shows that the architecture is of the dichasial type. The first two orders of branching are initiated from a dichasial branching without floral differentiation. The following orders present floral differentiation. They determine the formation of small units through the development of composite dichasium into biparous and uniparous cymes. This research makes it possible to establish a schematic representation of the first phases of inflorescence development and to define early stages of inflorescence morphogenesis.

scholarly journals Effect of Excess Silicon on the Formation of Ti3SiC2 Using Free Ti/Si/C Powders Synthesized via Arc Melting

ISRN Ceramics ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Mohamad Johari Abu ◽  
Julie Juliewatty Mohamed ◽  
Zainal Arifin Ahmad
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Relative Density ◽  
Stoichiometric Ratio ◽  
Secondary Phases ◽  
X Ray ◽  
Excess Silicon ◽  
Arc Melting ◽  
Equiaxed Grains ◽  
Scanning Electron

The aim of this study is to investigate the effect of excess silicon on the formation of Ti3SiC2 from free Ti/Si/C powders synthesized via arc melting. The reactant mixture was prepared according to the off-stoichiometric ratio of 3Ti : (x+1)Si : 2C, where x (excess Si) varied from 0 to 0.5. Samples were analyzed using X-ray diffractometry (XRD), field-emission scanning electron microscopy (FESEM), and energy-dispersive spectroscopy (EDS). The relative density and porosity of products were calculated using the Archimedes method. Through optimization of the arcing schedules (time) and excess Si amounts, 86.9 wt% of Ti3SiC2 with a relative density of 86% was obtained. For all products, Ti3SiC2 was identified as the main phase, while TiC, TiSi2, and Ti5Si3 were identified as secondary phases. Ti3SiC2 grains were in the form of elongated platelets; they were nucleated and grew on the surface of equiaxed TiC grains. The microporosity present in the TiC-equiaxed grains affected the density and porosity of the products.

scholarly journals The effect of phosphorus on solidification behaviour of undercooled Al–70 wt.%Si alloys

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Bo Dang ◽  
Zengyun Jian ◽  
Junfeng Xu
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Nucleation Rate ◽  
Growth Velocity ◽  
High Speed ◽  
Electromagnetic Levitation ◽  
Primary Silicon ◽  
High Speed Video ◽  
Equiaxed Grains ◽  
Scanning Electron

Abstract Effect of refining element phosphorus (P) on the morphology of the primary silicon in the Al–70 wt.%Si alloy was investigated via the electromagnetic levitation (EML) technique. The morphology and microstructure were analyzed by using high-speed video (HSV) and scanning electron microscopy (SEM). It was found that the morphology of primary silicon transformed from dendrites with several branches to blocky shape, and then to equiaxed grains in Al–70 wt.%Si and Al–70 wt.%Si–1.0 wt.%P alloys with increasing of undercooling. The nucleation number and nucleation rate increased exponentially with the increase of undercooling for both alloys. Finally, the growth velocity of primary silicon was discussed in combination with classical theory.

Comparison of Scanning Electron Microscopy and Light Microscopy for the Diagnosis of Early Stages of Brown Rot Wood Decay

IAWA Journal ◽  
1993 ◽  
Vol 14 (3) ◽  
pp. 219-226 ◽  
Author(s):  
W. Wayne Wilcox
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Light Microscopy ◽  
Cell Walls ◽  
Wood Decay ◽  
Brown Rot ◽  
Early Stages ◽  
Polarised Light ◽  
Scanning Electron

As part of a larger study of the microscopical characteristics useful in diagnosing early stages of decay, an opportunity was created to compare the ability of light microscopy (LM) and scanning electron microscopy (SEM) to image these features. Although most features could be imaged by both technologies, imaging was much easier in the SEM because it was being used at the low end of its resolution and magnification capability while the LM was near the high end of its limitations. One important feature which could not be imaged in SEM was the earliest attack on the cell walls, a feature which was visible under polarised light in the LM.

Preparation of Thick Ceramic Coating by Laser Multi-Layer Cladding II - Microstructural Characteristics

2013 ◽  
Vol 785-786 ◽  
pp. 901-905
Author(s):  
Dong Sheng Wang ◽  
Zong Jun Tian ◽  
Li Da Shen ◽  
Yin Hui Huang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Ceramic Coating ◽  
Ceramic Coatings ◽  
Microstructural Characteristics ◽  
Crack Control ◽  
Depth Direction ◽  
Clad Layer ◽  
Equiaxed Grains ◽  
Scanning Electron

In this study, thick ceramic coatings were fabricated by laser multi-layer cladding with Al2O3-13%TiO2nanostructured agglomerated powders based on series of crack control of clad layer. The microstructural characteristics and microhardness of the coating were investigated by using scanning electron microscopy (SEM) and microhardness measurement. The results show that the laser-clad thick ceramic coating has no obvious interface between the layers with dense, continuous structure, and almost no pores and free of large penetrating cracks. The ceramic layer is composed of fully melted regions (fine equiaxed grains) and partially melted regions (remained nanoparticles). In addition, the most microcracks in the coating are focus on the partially melted region. The grain size of ceramic coating in the depth direction is gradually increased, while the hardness along depth direction is gradually decreased.

scholarly journals Simulation of Incoherent Scattering in High-Angle Annular Dark-Field Scanning Electron Microscopy

2013 ◽  
Vol 19 (S2) ◽  
pp. 852-853
Author(s):  
A. Dutta ◽  
C. Reid ◽  
H. Heinrich
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Dark Field ◽  
Incoherent Scattering ◽  
High Angle ◽  
Annular Dark Field ◽  
Scanning Electron

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

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