The Influence of Inhomogeneous Deformation on the Microstructures and Properties of Thick-Plate 7150 Alloy

2013 ◽  
Vol 749 ◽  
pp. 250-254
Author(s):  
Feng Zhao ◽  
Ling Yong Cao ◽  
Yu Jing Lang ◽  
Hua Cui ◽  
Lin Zhong Zhuang ◽  
...  
Keyword(s):  
Surface Layer ◽  
Grain Boundaries ◽  
Hot Rolling ◽  
Thick Plate ◽  
Tensile Tests ◽  
Inhomogeneous Deformation ◽  
Average Width ◽  
Center Layer ◽  
Second Phases

The diversities and relations of microstructures and properties between the center and surface layer in thick-plate 7150 alloy were investigated by means of OM, TEM, SEM and tensile tests. The results indicated that the average width of elongated grains with fewer substructures in the center of hot-rolling thick plate is about 2 times larger than that in the surface layer. The coarser second phases are massed up at the grain boundaries of the center layer while those are crushed into smaller particles in the surface layer. By aging, the strengthening precipitates in the center are mainly GP zone and η' phase, while in the surface layer η' and η phases play the main roles. Consequently, the strength is about 80Mpa (15%) higher in the center than in the surface, with lower elongations (26% lower).

Deformation and fracture of high-entropy AlCoCrFeNi alloy

2021 ◽  
pp. 103-108
Author(s):  
Yu.F. Ivanov ◽  
◽  
V.E. Gromov ◽  
K.A. Osintsev ◽  
S.V. Konovalov ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Tensile Tests ◽  
High Entropy Alloy ◽  
Second Phase ◽  
High Entropy ◽  
Deformation And Fracture ◽  
Distribution Of Elements ◽  
Microscopy Method ◽  
Second Phases ◽  
Wire Arc Additive Manufacturing

Using wire-arc additive manufacturing (WAAM)technology in an atmosphere of argon gas a non - equatomic high entropy alloy (HEA) of AlCoCrFeNi system is obtained: Al (35.67±1.34 at%), Ni (33.79±0.46 at%), Fe (17.28±1.83 at%), Cr (8.28±0.15 at%), Co (4.99±0.09 at%). Scanning electron microscopy method revealed that HEA is a polycrystal material having the grain size (4-15) µm with the particles of second phase located along the grain boundaries. Mapping methods showed that grain volumes are enriched in aluminum and nickel, while grain boundaries contain chromium and iron. Cobalt is distributed in the crystal lattice of the resulting HEA quasi-uniformly. It is shown that during tensile tests, the material was destroyed by the mechanism of intra-grain cleavage. The formation of brittle cracks along the boundaries and at the junctions of grain boundaries, i.e., in places containing inclusions of the second phases, is revealed. It was suggested that one of the reasons for the increased brittleness of HEA, is revealed uneven distribution of elements in the microstructure of the alloy and also the presence in the volume of material discontinuities of various shapes and sizes.

Orientation Evolutions During Hot Rolling of Electrical Steel Containing Initial Columnar Grains

2011 ◽  
Vol 702-703 ◽  
pp. 754-757 ◽  
Author(s):  
Ping Yang ◽  
Y.Y. Shao ◽  
W.M. Mao ◽  
Q.W. Jiang ◽  
W.X. Jin
Keyword(s):  
Grain Boundaries ◽  
Hot Rolling ◽  
Electrical Steel ◽  
Texture Evolution ◽  
Center Layer ◽  
Different Types ◽  
Columnar Grains ◽  
The Difference ◽  
Ebsd Technique ◽  
Hot Rolled

The texture evolution in the surface and center layer of hot rolled electrical steel containing initial columnar grains with their <100> nearly along ND, RD and TD of sheets were determined by EBSD technique. The transition from Goss to Brass or Copper orientation in surface was analyzed. The difference in texture of center layers in these samples was compared. In particular, orientation evolutions within grains and at grain boundaries of different types of orientations were explored. The results are discussed in terms of the special alignments of grain boundaries among columnar grains.

Microstructure and Tensile Properties Anisotropy of 7xxx Ultra-Thick Plate

2021 ◽  
Vol 1035 ◽  
pp. 134-142
Author(s):  
Ze Yu Zhou ◽  
Xiang Xiao ◽  
Wen Jing Zhang ◽  
Feng Chun Wang ◽  
Wei Cai Ren ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Tensile Property ◽  
Thick Plate ◽  
Tensile Tests ◽  
Thickness Direction ◽  
Center Layer ◽  
Transmission Electron ◽  
Back Scattering ◽  
Scanning Electron

The microstructure，texture distribution and tensile property of 7xxx ultra-thick plate was investigated by optical microscopy (OM), scanning electron microscopy (SEM), electron back scattering diffraction (EBSD), transmission electron microscopy (TEM) and tensile tests. The results show that the microstructure, texture and tensile property were inhomogeneous along the thickness direction. A large number of sub-crystals remained on the surface of the thick plate and was accompanied by much recrystallization. Most of the structures were random texture, and the proportion of typical texture was low at the edge. For the center layer, there were also a lot of recrystallized grains and typical deformed texture along the β-fiber (Brass, S, and Copper) was observed. The 1/4 layer of the plate is a transition one, and had the lowest recrystallized fraction. From surface to center, precipitation phases within grains and grain boundaries gradually coarsen, mechanical properties reduced. At the same thickness, the tensile property showed appreciable anisotropy, the L direction was the highest and the S direction was the lowest.

Slip traces caused by plastic deformation during recrystallization of thin metal sheets

1994 ◽  
Vol 52 ◽  
pp. 620-621
Author(s):  
H. Lin ◽  
D. P. Pope
Keyword(s):  
Grain Size ◽  
Grain Boundaries ◽  
Sample Thickness ◽  
List Type ◽  
Metal Sheets ◽  
Second Phases ◽  
Slip Traces ◽  
Series Of Experiments ◽  
Cold Rolled ◽  
Individual Grains

During a study of mechanical properties of recrystallized B-free Ni3Al single crystals, regularly spaced parallel traces within individual grains were discovered on the surfaces of thin recrystallized sheets, see Fig. 1. They appeared to be slip traces, but since we could not find similar observations in the literature, a series of experiments was performed to identify them. We will refer to them “traces”, because they contain some, if not all, of the properties of slip traces. A variety of techniques, including the Electron Backscattering Pattern (EBSP) method, was used to ascertain the composition, geometry, and crystallography of these traces. The effect of sample thickness on their formation was also investigated.In summary, these traces on the surface of recrystallized Ni3Al have the following properties:1.The chemistry and crystallographic orientation of the traces are the same as the bulk. No oxides or other second phases were observed.2.The traces are not grooves caused by thermal etching at previous locations of grain boundaries.3.The traces form after recrystallization (because the starting Ni3Al is a single crystal).4.For thicknesses between 50 μm and 720 μm, the density of the traces increases as the sample thickness decreases. Only one set of “protrusion-like” traces is visible in a given grain on the thicker samples, but multiple sets of “cliff-like” traces are visible on the thinner ones (See Fig. 1 and Fig. 2).5.They are linear and parallel to the traces of {111} planes on the surface, see Fig. 3.6.Some of the traces terminate within the interior of the grains, and the rest of them either terminate at or are continuous across grain boundaries. The portion of latter increases with decreasing thickness.7.The grain size decreases with decreasing thickness, the decrease is more pronounced when the grain size is comparable with the thickness, Fig. 4.8.Traces also formed during the recrystallization of cold-rolled polycrystalline Cu thin sheets, Fig. 5.

scholarly journals Effect of Crystallographic Orientation and Grain Boundaries on Martensitic Transformation and Superelastic Response of Oligocrystalline Fe–Mn–Al–Ni Shape Memory Alloys

2021 ◽  
Author(s):  
A. Bauer ◽  
M. Vollmer ◽  
T. Niendorf
Keyword(s):  
Martensitic Transformation ◽  
Grain Boundary ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Grain Boundaries ◽  
Tensile Tests ◽  
Image Correlation ◽  
Stress Concentrations ◽  
Grain Orientations ◽  
High Degree

AbstractIn situ tensile tests employing digital image correlation were conducted to study the martensitic transformation of oligocrystalline Fe–Mn–Al–Ni shape memory alloys in depth. The influence of different grain orientations, i.e., near-〈001〉 and near-〈101〉, as well as the influence of different grain boundary misorientations are in focus of the present work. The results reveal that the reversibility of the martensite strongly depends on the type of martensitic evolving, i.e., twinned or detwinned. Furthermore, it is shown that grain boundaries lead to stress concentrations and, thus, to formation of unfavored martensite variants. Moreover, some martensite plates seem to penetrate the grain boundaries resulting in a high degree of irreversibility in this area. However, after a stable microstructural configuration is established in direct vicinity of the grain boundary, the transformation begins inside the neighboring grains eventually leading to a sequential transformation of all grains involved.

scholarly journals Processing of Bi–Sr–Ca–Cu–O glasses using platinum and alumina crucibles

1992 ◽  
Vol 7 (8) ◽  
pp. 2035-2039 ◽  
Author(s):  
T.G. Holesinger ◽  
D.J. Miller ◽  
S. Fleshler ◽  
L.S. Chumbley
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Grain Boundaries ◽  
Annealed Sample ◽  
Substrate Material ◽  
Superconducting Phase ◽  
Transition Temperatures ◽  
Secondary Phases ◽  
Second Phases ◽  
Potential Substrate

Reactions with alumina and platinum crucibles were studied during the preparation of Bi2Sr2Ca1Cu2Oy “2212” glasses. In particular, reactions with Al2O3 are of interest since alumina is a potential substrate material in applications of this superconductor. Glasses processed using alumina crucibles were completely homogeneous and free of secondary phases although the material contained 2.26 at. % Al in solution. After heat treatments, Al was found in the form of SrCaAlOy particles located primarily along grain boundaries of the 2212 superconducting phase. Platinum contamination was minimal (<0.02 at. %) and no Pt-containing secondary phases were found in amorphous or annealed samples. Glasses made with Pt crucibles were found to contain small amounts of CaO, Sr14−xCaxCu24O41, and 2201 as second phases. Differential thermal analysis (DTA) suggested that the crystallization processes were essentially the same for all samples although the small amount of Al seemed to slow the kinetics leading to the formation of 2212. Neither Al nor Pt was detected within the 2212 phase. The measured superconducting compositions in each annealed sample were nearly the same with identical transition temperatures of 88 K. Overall differences in stoichiometry were accommodated by changes in the number and composition of the secondary phases present.

Effect of Additional Shear Strain Layer on Microstructure and Tensile Strength of Fine Wire

2007 ◽  
Vol 340-341 ◽  
pp. 525-530 ◽  
Author(s):  
Satoshi Kajino ◽  
Motoo Asakawa
Keyword(s):  
Tensile Strength ◽  
Surface Layer ◽  
Tensile Test ◽  
Shear Strain ◽  
Crystal Orientation ◽  
Hardened Layer ◽  
High Tensile Strength ◽  
Center Layer ◽  
Fine Wire ◽  
Strain Layer

The mechanical and electrical applications of fine wires (D = 0.1 mm) has become more widely spread. In general, it is well known that fine drawn wires have high tensile strength while maintaining ductility. It has been determined that a hardened layer of around 0.04 mm in depth, referred to as the “additional shear strain layer,” is generated beneath the surface layer of the wire, and this additional shear strain layer affected the tensile strength of the fine wire. As an origin of this phenomenon, it was ascertained that the microstructure of surface layer was finer than that of center layer. The purpose of this paper is to investigate the effect of die angle on the microstructure and the tensile strength of the additional shear strain layer. The tensile test was performed as the surface layer was thinned by electro-polishing, and the crystal orientation and the crystal grain were measured via EBSD. As a result, it was ascertained that die angle affected the tensile strength and crystal grain refinement of the additional shear stray layer.

Effect of Plastic Deformation on the Mechanical Properties and Microstructure of Homogenized AZ80 Magnesium Alloy

2010 ◽  
Vol 139-141 ◽  
pp. 180-184
Author(s):  
Yong Xue ◽  
Zhi Min Zhang ◽  
Li Hui Lang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Grain Boundaries ◽  
Gradual Increase ◽  
Tensile Tests ◽  
Extrusion Ratio ◽  
Extrusion Temperature ◽  
Second Phase ◽  
Strength And Plasticity ◽  
Az80 Alloy

In the present research, the influences of different extrusion ratios (15, 30, 45, 60, and 75) and extrusion temperatures (300°C, 330°C, 360°C, 390°C, 420°C) on the mechanical properties and microstructure of homogenized AZ80 alloy have been investigated through the tensile tests and via metallographic microscope observation. The results show that the alloy’s grain is small and small amounts of black hard and brittle second-phase β (Mg17Al12) are precipitated uniformly along the grain boundary causing the gradual increase of the alloy’s tensile strength at 330°C. When the extrusion temperature is up to 390°C, the grain size increases significantly, but the second phase precipitation along grain boundaries transforms into continuous and uniform-distribution precipitation within the grain. In this case, when the extrusion ratio is 60, the alloy’s tensile strength reaches its peak 390Mpa. As the extrusion temperature increases, inhomogeneous precipitation of the second-phase along grain boundaries increases, causing the decrease of the alloy’s strength. At the same temperature, the tensile strength increases firstly and then decreases as extrusion ratio increases. With the gradual increase of the refinement grain, the dispersed precipitates increase and the alloy’s tensile strength and plasticity reach their peaks when the extrusion temperature is 390°C. As the grain grows, the second phase becomes inhomogeneous distribution, and the alloy’s strength and plasticity gradually decrease.

Effect of Ca and Sr Content on Elevated Temperatures Mechanical Properties of a Cast AZ91 Magnesium Alloy

2007 ◽  
Vol 26-28 ◽  
pp. 141-144
Author(s):  
Ippei Takeuchi ◽  
Kinji Hirai ◽  
Yorinobu Takigawa ◽  
Tokuteru Uesugi ◽  
Kenji Higashi
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Creep Resistance ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Az91 Magnesium Alloy ◽  
Additional Amount ◽  
Az91 Magnesium ◽  
Second Phases

The effect of Ca and Sr content on the microstructure and mechanical properties of a cast AZ91 magnesium alloy is investigated. Ca and Sr additions in AZ91 magnesium alloy are expected high creep resistance. The microstructure of the alloy exhibits the dendritic α-matrix and the second-phases forming networks on the grain boundary. Tensile tests at elevated temperatures between 448 and 523K reveal that the creep resistance was improved with increasing the additional amount of Ca, especially more than 1.0wt%. From the perspective of grain refinement effect, it is expected that the additions of Ca and Sr to AZ91 magnesium alloy not only improve creep resistance but also improve mechanical properties at room temperature.

Mechanism of Quality Factor Compensation by Nb2O5 Addition for Dielectric Properties of Low-T Sintered ZST Microwave Ceramics

2000 ◽  
Vol 658 ◽  
Author(s):  
Yong H. Park ◽  
Moo Y. Shin ◽  
Hyung H. Kim ◽  
Kyung H. Ko
Keyword(s):  
Dielectric Properties ◽  
Grain Boundaries ◽  
Quality Factor ◽  
Microwave Dielectric Properties ◽  
Microwave Ceramics ◽  
Microwave Dielectric ◽  
Post Annealing ◽  
X Band ◽  
Second Phases ◽  
Nb Addition

ABSTRACTIt has been known that some additives such as Nb2O5 are efficient quality factor compensators to potential additives for low-T sintering of (Zr0.8Sn0.2)TiO4such asZnO. The compensation mechanism of Nb2O5was analyzed in the light of its effects on the Zn incorporation in grains. ZST ceramics were prepared by conventional mixed oxide method and their microwave dielectric properties including quality factor, permittivity and temperature coefficient frequency (TCF) were measured at X-band. After sintering at 1350 and 1400oC, samples were post-annealed at 900∼1100oC. It was found that as Nb2O5 was added, the quality factor of 6 mol % ZnO-ZST specimens increased from 24000 to 44000 without any sacrificing of other dielectric properties such as permittivity and TCF. According to TEM and XRD, Nb addition tends to enhance Zn diffusion toward grain boundaries while Nb moved in the opposite direction. Due to the fact that no second phases were formed, it was assumed that the redistribution of Zn and Nb could play a major role in the enhancement mechanism of quality factor. Post-annealing can also be a secondary booster for the quality factor of ZST. After annealing at 900∼1100oC, the quality factor of a specimen with additives, increased again up to 48000 due to further decrease of oxygen vacancies resulting from further out-diffusion of Zn toward grain boundaries and incorporation of Nb into the grain.

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