The Heterogeneity of Composition and Microstructure in Cast Large Sized 3104 Alloy Slab

2012 ◽  
Vol 217-219 ◽  
pp. 349-353
Author(s):  
Rui Yin Huang ◽  
Zhi Min Yin ◽  
Yuan Zhi Zhu
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Aluminium Alloy ◽  
Cooling Rate ◽  
Surface Area ◽  
Cross Section ◽  
Chemical Compositions ◽  
The Cross

Heterogeneity of composition and microstructure in cast large sized 3104 aluminium alloy slab were studied using AES-ICP, OM, SEM, etc. The results show that the cooling rate on the cross section of 3104 slab is different, macro-segregation is found in the different section in the slab .The content of Ti decreases gradually from the surface to about 1/4 thickness of the slab, then increases rapidly to the center of slab; other elements content increases gradually from the surface to the about 1/4 thickness and then decreases rapidly to the center; the grain size on the surface area is fine, and the grain size at the center is coarse , segregation of Mg is found within the grains; great amount compound is found to be of presence on the grain boundary, with chemical compositions of Al 87（FeMn）13 and Al83（FeMn）12Si5; The compound size at the surface area is comparatively smaller, and coarser at the centre of slab.

Effects of resolution on the measurement of grain ‘size’

1985 ◽  
Vol 49 (353) ◽  
pp. 539-546 ◽  
Author(s):  
R. Dearnley
Keyword(s):  
Grain Size ◽  
Image Analysis ◽  
Grain Boundary ◽  
Surface Area ◽  
Unit Volume ◽  
Fractal Dimensions ◽  
Size Analysis ◽  
Automatic Image Analysis ◽  
Fine Grained ◽  
Kinetics Of

AbstractMeasurements of fine-grained dolerites by optical automatic image analysis are used to illustrate the effects of magnification and resolution on the values obtained for grain ‘size’, grain boundary length, surface area per unit volume, and other parameters. Within the measured range of optical magnifications (× 26 to × 3571) and resolutions (1.20 × 10−3 cm to 8.50 × 10−6 cm), it is found that the values of all grain parameters estimated by chord size analysis vary with magnification. These results are interpreted in terms of the concepts of ‘fractal dimensions’ introduced by Mandelbrot (1967, 1977). For some comparative purposes the fractal relationships may be of little significance as relative changes of size, surface area, and other parameters can be expressed adequately at given magnification(s). But for many studies, for instance in kinetics of grain growth, the actual diameter or surface area per unit volume is an important dimension. The consequences are disconcerting and suggest that it may be difficult in some instances to specify the ‘true’ measurements of various characteristics of fine-grained aggregates.

Study on the Porosity in Al-Zn-Mg-Cu High Strength Alloy DC Ingot

2016 ◽  
Vol 879 ◽  
pp. 790-794 ◽  
Author(s):  
Hui Xue Jiang ◽  
Hiromi Nagaumi ◽  
Shi Jie Guo ◽  
Chun Zou
Keyword(s):  
Cooling Rate ◽  
Cross Section ◽  
High Strength ◽  
Direct Chill ◽  
Thickness Direction ◽  
X Ray ◽  
Density Method ◽  
Width Direction ◽  
Strength Alloy ◽  
The Cross

An Al-Zn-Mg-Cu high strength alloy ingot produced by Direct-Chill casting was used in this study. The distribution of porosity in the cross section of the DC ingot was investigated by the precision density method (Archimeds’ principle), also X-ray microtomography technique was used to quantitatively analyze porosities in typical positions. The pattern in the cross section as well as in the thickness and width direction was obtained. The results show that: in the cross section of the ingot, porosity was increasing gradually from the surface to the center of the ingot; porosity shows an overall escalating trend from the surface to the center of the ingot both in thickness direction and in width direction; porosity was closely related to the cooling rate in the ingot; oxide inclusions have an effect on the formation of porosity to some extent.

The Strength and Ductility of 5483 Aluminium Alloy Processed by Various SPD Methods

2013 ◽  
Vol 765 ◽  
pp. 423-428 ◽  
Author(s):  
Piotr Bazarnik ◽  
Barbara Romelczyk ◽  
Mariusz Kulczyk ◽  
Małgorzata Lewandowska
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Mechanical Strength ◽  
Aluminium Alloy ◽  
Microstructural Analysis ◽  
Boundary Misorientation ◽  
Size Refinement ◽  
Specific Strength ◽  
Angular Pressing ◽  
Significant Difference

Grain size refinement is an efficient way to improve mechanical strength and thus make light metals even lighter in terms of specific strength. However, the strength improvement is at the expense of ductility. Therefore, a better understanding of microstructural factors influencing both parameters is of prime importance for further development of ultrafine grained materials. In this work, we report results obtained for 5483 aluminium alloy which was subjected to several severe plastic deformation (SPD) methods, i.e. equal channel angular pressing (ECAP), Hydrostatic Extrusion (HE) and the combination of the two. Detailed microstructural analysis revealed significant difference in the grain size and grain boundary characteristics between samples obtained following different routes. It was found that although the grain size is a prime microstructural parameter determining mechanical strength, second order factors such as grain size distribution and distribution of grain boundary misorientation angles also play a significant role.

scholarly journals The observation of surface-softening in Fe-based metallic glass

2011 ◽  
Vol 1300 ◽  
Author(s):  
Ansar Masood ◽  
V. Ström ◽  
L. Belova ◽  
J.J. Oak ◽  
J. Ågren ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Metallic Glass ◽  
Cooling Rate ◽  
Cross Section ◽  
Radial Dependence ◽  
Depth Sensing ◽  
Nano Indentation ◽  
Outermost Surface ◽  
The Cross ◽  
Significant Change

ABSTRACTDepth sensing nano-indentation investigations have been performed to determine the radial dependence of the hardness through the cross section of a Fe-based bulk glassy rod. We have found the hardness of the material decreases along radius from the centre to the outermost surface. This phenomenon is attributed to the ‘cooling rate induced surface softening’. Furthermore, a significant change (~15 %) in elastic modulus is noticed along the radius as well.

scholarly journals The Effect of Microstructure of Molybdenum Target

2021 ◽  
Author(s):  
Geng An ◽  
Jun Sun
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Grain Boundary ◽  
Surface Area ◽  
Grain Orientation ◽  
Deposition Velocity ◽  
Grain Structures ◽  
The Difference ◽  
Morphological Differences ◽  
Effect Of Microstructure

Abstract: Molybdenum (Mo) thin films were sputtered from two kinds of Mo targets with different microstructures under the same sputtering process, and the effect of microstructure of Mo target on morphology, deposition rate and resistance of sputtered film were studied and discussed. The results show that morphological differences between Mo thin films sputtered by Mo targets with different microstructures are very small. The more uniform and finer the grain structures of Mo target, the better the uniformity on thickness and resistance of Mo sputtered film. Moreover, during sputtering process, when Mo target’s grain size is finer and the surface area of grain boundary is higher, the thickness reduction of the target is more homogeneous and the sputtering film has faster deposition velocity. The difference in microstructure of the Mo target has not obvious influence on the grain orientation of sputtering film.

Grain size of MgO and polymorphic phases of ZrO2 in zirconia-toughened MgO

1993 ◽  
Vol 8 (11) ◽  
pp. 2757-2760 ◽  
Author(s):  
Yasuro Ikuma ◽  
Toshio Sugiyama ◽  
Junko Okano
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Cooling Rate ◽  
Grain Growth ◽  
Room Temperature ◽  
Boundary Limit ◽  
Transmission Electron ◽  
Electron Microscopes

Zirconia-toughened MgO was manufactured and examined by scanning and transmission electron microscopes. It was found that ZrO2 particles that are present on the MgO grain boundary limit the grain growth of MgO. The cooling rate has an effect on the ZrO2 phase in zirconia-toughened MgO fired in a cubic ZrO2–MgO field, but it does not have an effect on the ZrO2 phase in specimens fired in a tetragonal ZrO2–MgO field. Tetragonal ZrO2 was retained at room temperature in zirconia-toughened MgO.

Numerical Simulation and Online Window Monitoring of SPR Process

2012 ◽  
Vol 602-604 ◽  
pp. 1765-1768 ◽  
Author(s):  
Xiao Cong He ◽  
Yue Bo Hu ◽  
Bao Ying Xing ◽  
Yan Fang Ding ◽  
Kai Zeng
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Aluminium Alloy ◽  
Cross Section ◽  
Fuel Efficiency ◽  
Experimental Tests ◽  
Advanced Materials ◽  
Monitoring Technique ◽  
The Cross

The need to create lighter vehicles to aid in reducing emissions and increase fuel efficiency has become increasingly important in recent years. Self-pierce riveting (SPR) has drawn more attention as it can join some advanced materials that are dissimilar and hard to weld. In present study, the SPR process has been numerically simulated using the commercial finite element (FE) software LS-Dyna. For validating the numerical simulation of the SPR process, experimental tests on specimens made of aluminium alloy have been carried out. The online window monitoring technique was used in the tests for evaluating the quality of SPR joints. Good agreements between the simulations and the tests have been found, both with respect to the force-travel curves as well as the deformed shape on the cross-section of SPR joint.

scholarly journals First-Order Size Effects in the Mechanics of Miniaturized Components

2008 ◽  
Vol 13-14 ◽  
pp. 183-192 ◽  
Author(s):  
J.P.M. Hoefnagels ◽  
P.J.M. Janssen ◽  
T.H. de Keijser ◽  
M.G.D. Geers
Keyword(s):  
Free Surface ◽  
Grain Boundary ◽  
Cross Section ◽  
Stress Level ◽  
Size Effects ◽  
Uniaxial Tensile ◽  
Order Effects ◽  
First Order ◽  
Single Grain ◽  
The Cross

This work analyses those size effects that are encountered first upon downscaling, including grain boundary effects, free surface effects, grain statistics effects. The separate influence of first-order effects was carefully investigated from uniaxial tensile tests on high-purity aluminum specimens with a well-defined microstructure of through-thickness grains, whereby the total number of grains in the cross-section was reduced towards a single grain in a cross-section by, first, decreasing the film thickness and, second, for specimens with through-thickness grains decreasing the specimen width. In addition, 3D dislocation-field strain gradient plasticity simulations were employed to analyze the intrinsic size effects, using the grain size and texture as measured experimentally. The work shows that for miniaturized structures with a limited number of columnar grains a unique Hall-Petch relation does not exist, even though a grain boundary effect, i.e. a decrease in stress level (at a given strain) for decreasing grain boundary area per unit volume, is clearly present. When the microstructure is kept constant upon miniaturization, the free surface per unit area increases causing the stress level of the structure to decrease, the effect of which increases towards a single grain in the cross-section. In addition, the work shows that grain statistics effects also contribute to observed weakening, due to insufficient compensation of local (weaker) material properties by the surrounding material (i.e. grains). Finally, grain statistics also significantly increase the statistical variation in mechanical properties for small-sized structures, an effect that is especially important for the reliability of miniature components. The separate influence of these first-order effects as well as their interplay are explained in terms of the movement of the dislocations upon plastic flow.

Silica Additions and the Performance of PTC Thermistors

2006 ◽  
Vol 45 ◽  
pp. 2362-2370
Author(s):  
Colin Leach ◽  
M. Zubair ◽  
Robert Freer
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Cooling Rate ◽  
Microstructural Development ◽  
Electrical Behaviour ◽  
Cooling Rates ◽  
Sample Density

A series of PTC thermistors, based on BaTiO3, doped with Ca, Mn and Y, were prepared with additions of SiO2 at levels of 0, 1, 2 and 3 at. %. The effect of the SiO2 additions and cooling rate on microstructural development and bulk performance were characterised using a combination of SEM, EBSD, and R-T experiments. It was found that the addition of SiO2 increased grain size marginally, and decreased sample density by reducing the amount of grain-grain contact. The addition of SiO2 also modified the distribution of grain boundary types by systematically decreasing the proportion of low-Σ grain boundaries within the microstructure. Electrical behaviour was modified by adding SiO2 or increasing the sample cooling rates; in both cases there was an increase in ρ25 and a decrease in ρmax, with ρmax also being displaced to higher temperatures.

Evidence for a Grain Boundary Grooving Model of Agglomeration in Polycrystalline Tisi2 Thin Films

1990 ◽  
Vol 202 ◽  
Author(s):  
Thomas Nolan ◽  
Robert Beyers ◽  
Robert Sinclair
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Grain Boundary ◽  
Cross Section ◽  
Boundary Energy ◽  
Film Surface ◽  
Grain Boundary Energy ◽  
Surface And Interface ◽  
Si Substrates ◽  
Polycrystalline Thin Films

ABSTRACTAn equilibrium model for agglomeration based upon the mechanism of grain boundary grooving in polycrystalline thin films is suggested. It involves an energy balance between surface, interface, and grain boundary energies, and predicts parameters which will influence the onset of agglomeration. It has been determined that small grain size, low grain boundary energy, high film surface and interface energies, and growth of single crystal epitaxial layers should promote resistance to agglomeration. Polycrystalline TiSi2 thin films deposited on Si substrates have been observed using cross-section TEM. The micrographs provide evidence that, for these films, the grain boundary grooving mechanism is dominant and most of the modeling assumptions are valid.

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