The Dual Nature of Precipitates in Al-Mg-Si Alloys

2010 ◽  
Vol 638-642 ◽  
pp. 390-395 ◽  
Author(s):  
Sigmund J. Andersen ◽  
Calin D. Marioara ◽  
René Vissers ◽  
Malin Torsæter ◽  
Ruben Bjørge ◽  
...  
Keyword(s):  
Material Properties ◽  
Mirror Plane ◽  
Precipitation Process ◽  
Dual Nature ◽  
Cu Alloys ◽  
Main Plane ◽  
Super Cell ◽  
The Matrix ◽  
Hexagonal Arrangement ◽  
Al Matrix

Precipitates in Al-Mg-Si-(Cu) alloys all contain a similar hexagonal arrangement of Si-atoms. Precipitates come and go but their inner Si ordering appears to vary little throughout the precipitation process. In order to improve understanding of precipitation and the related material properties, it is becoming increasingly clear that this includes a good understanding of the hexagonal Si-network, its relation to the precipitates and the Al matrix. Previous studies have revealed that adding Cu atoms to the ternary system, causes the Si network to twist slightly in the matrix about its hexagonal axis, favoring different precipitates. Here we investigate these two rotations. It is shown they can be viewed as a mirror of the network itself about a {310} Al plane. Since precipitates are coherent, the Si-network with its triangular arrangements of Si must also match a fourfold arrangement of Al on the {100} planes. Sets of Al lattice positions exist which can approximate the tree-fold Si symmetry, according to the experimentally observed orientations, and one or more large super-cells can be found having near fit in both lattices. The mirror plane is a main plane in one such super-cell. We show that the mirror leaves every seventh node of the network unchanged, thus defining a smaller hexagonal super-cell in the network, similar to the B’ or Q’/Q phase, where corners are invariant, but where the Si contents is flipped.

GPB zones as a precursor for S’ precipitation in Al-based matrices

1996 ◽  
Vol 54 ◽  
pp. 996-997
Author(s):  
V. Radmilovic ◽  
S. Ratkovic ◽  
G.J. Shiflet ◽  
U. Dahmen
Keyword(s):  
Size Structure ◽  
Early Stage ◽  
Atomic Level ◽  
Zone Size ◽  
Zone Structure ◽  
Cu Alloys ◽  
Resolution Electron ◽  
The Matrix ◽  
Crystallographic Orientation Relationship ◽  
Al Matrix

In the pseudo-binary Al-Al2CuMg alloy, the Cu/Mg-rich precipitation zones (GPB) are able to cause considerable hardening of the matrix. The hardening is apparently not very sensitive to the zone size or degree of ordering. According to Silcock these zones are cylindrical, 1-2 nm in diameter and 4 nm long. They are also formed during the early stage of aging at 190°C and are followed by nucleation of S’ precipitates with {210} habit plane. Overaging occurs by the further formation and growth of S’ with a corresponding re-solution of GPB zones. Since the discovery of GP zones (reach in Cu) in Al-Cu alloys by Guinier and Preston, the structure of these zones, even at atomic level, has been studied extensively. However, there are very few studies of GPB zone structure and crystallographic relationship with Al matrix. In this paper results using atomic resolution electron microscopy on the GPB zone size, structure and crystallographic orientation relationship with Al matrix are reported.

Monitoring the Evolution of the Matrix Copper Composition in Age Hardenable Al-Cu Alloys

2006 ◽  
pp. 591-596
Author(s):  
Kate M. Nairn ◽  
Brian M. Gable ◽  
Rüdiger Stark ◽  
Natalie Ciccosillo ◽  
Anita J. Hill ◽  
...  
Keyword(s):  
Cu Alloys ◽  
The Matrix

Grey cast irons for thermal-stress applications

1970 ◽  
Vol 5 (2) ◽  
pp. 98-109 ◽  
Author(s):  
R Bertodo
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Material Properties ◽  
Alternative Assessment ◽  
Flake Graphite ◽  
Cast Irons ◽  
Mechanical And Physical Properties ◽  
The Matrix ◽  
Grey Cast ◽  
Engine Components

Pearlitic flake-graphite grey cast irons have long been widely used for the manufacture of diesel-engine combustion-chamber components. Nonetheless, very few pertinent high-temperature data are to be found in published work. The investigation described attempts to enlarge current knowledge on the high-temperature behaviour of grey cast irons in view of requirements highlighted by high thermal ratings. A general consideration of the problem showed that the often quoted Eichelberg material-quality factor is largely irrelevant and an alternative assessment formula is proposed. This is broadly confirmed by a systematic examination of the mechanical and physical properties of 166 plain and alloyed cast irons and a limited number of engine components. Different engine components impose different demands upon the material properties but for economic reasons a single cast-iron melt capable of meeting most of the requirements of all components is needed. It is shown that this situation is best met with an alloyed iron containing 1.3 per cent of copper-nickel and 0.4 per cent of molybdenum. The scatter in properties obtained from production casts was found to be typical for such irons. For components having safety factors of 2 or less, a prerequisite of economic engineering design, the service reliability is crucially dependent upon the scatter of material properties. Thus, there are advantages in reducing this scatter and it is shown that this can be achieved by attention to the cleanliness of the matrix and tight control of the chemistry of the melt. In general, the absolute values of mechanical and physical properties of flake-graphite cast irons appear to be governed mainly by the form and size of the graphite flakes and the chemistry of the matrix (i.e. CEV and alloying additions). Regression analysis of the results permitted the derivation of empirical formulae for the prediction of the iron properties. The general findings are used to suggest possible ways of improving the thermal resistance.

Study on the Effects of the Nonhomogeneous Material Properties on the Structure Strength of the Induction Quenched Crankshaft

2014 ◽  
Vol 703 ◽  
pp. 400-405
Author(s):  
Ji Shan Li ◽  
Ri Dong Liao ◽  
Guo Hua Chen
Keyword(s):  
Elastic Modulus ◽  
Material Properties ◽  
Fem Model ◽  
Explosion Pressure ◽  
Nonhomogeneous Material ◽  
Linear Rule ◽  
Distribution Rule ◽  
The Matrix ◽  
Nonhomogeneous Properties ◽  
Structure Strength

To study the effects of the nonhomogeneous material properties on the stress in an induction quenched crankshaft, the FEM model considering the nonhomogeneous material properties was established to simulate the stress in the crankshaft under the explosion pressure. Results showed that the nonhomogeneous properties almost didn’t vary the Mises stress distribution rule in the crankshaft. The maximum Mises stress, the ratio of the elastic modulus of the surface layer and the matrix followed a linear rule nearly. Moreover, the maximum Mises stress increased with the ratio. Besides, effect of elastic modulus distribution in the transition layer on the maximum stress could be ignored. To simplify the establishment of the FEM model, the elastic modulus could be set to either equal to the surface layer’s or the matrix’s.

Orientation Studies of α-Al(Fe,Mn)Si Dispersoids in 3xxx Al Alloys

2014 ◽  
Vol 794-796 ◽  
pp. 39-44 ◽  
Author(s):  
Astrid Marie Flattum Muggerud ◽  
Yan Jun Li ◽  
Randi Holmestad
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Orientation Relationship ◽  
Aluminum Matrix ◽  
Al Alloys ◽  
Orientation Relationships ◽  
The Matrix ◽  
The Common ◽  
Habit Planes ◽  
Al Matrix

Dispersoids are important in 3xxx Al alloys, influencing mechanical properties, texture and recrystallization. In this work α-Al (Fe,Mn)Si dispersoids have been studied after low temperature homogenisation. The common orientation relationship between dispersoids and Al matrix has been reported in earlier studies. Here a systematic study on the orientation relationship and its exceptions is presented. It is found that most of the dispersoids follow the common orientation relationship, [1-1 1] α //[1-1 1]Al , (5-2 -7 ) α //(0 1 1)Al . Here the dispersoids are semi coherent with the Aluminum matrix. Different morphologies and habit planes are possible. Deviations from the most commonly observed orientation relationships are presented and discussed, to underline the complexity of the phase and its relation to the matrix.

Microstructures and Mechanical Properties of 6061 Al Matrix Smart Composite Containing TiNi Shape Memory Fiber

1996 ◽  
Vol 459 ◽  
Author(s):  
J. H. Lee ◽  
K. Hamada ◽  
K. Miziuuchia ◽  
M. Taya ◽  
K. Inoue
Keyword(s):  
Mechanical Properties ◽  
Shape Memory ◽  
Elevated Temperatures ◽  
Volume Fraction ◽  
Matrix Material ◽  
Matrix Alloy ◽  
Flow Strength ◽  
The Matrix ◽  
Shape Memory Fiber ◽  
Al Matrix

ABSTRACT6061 Al-matrix composite with TiNi shape memory fiber as reinforcement has been fabricated by vacuum hot pressing to investigate the microstructure and mechanical properties. The yield stress of this composite increases with increasing amount of prestrain, and it also depends on the volume fraction of fiber and heat treatment. The smartness of the composite is given due to the shape memory effect of the TiNi fiber which generates compressive residual stresses in the matrix material when heated after being prestrained. Microstructual observations have revealed that interfacial reactions occur between the matrix and fiber, creating two intermetallic layers. The flow strength of the composite at elevated temperatures is significantly higher than that of the matrix alloy without TiNi fiber.

Microstructure Evolution during Thermal Aging of Fe-Cu Alloys

2012 ◽  
Vol 488-489 ◽  
pp. 164-168
Author(s):  
Jiu Zhou Zhao ◽  
Qing Liang Wang
Keyword(s):  
Microstructure Evolution ◽  
Thermal Aging ◽  
Late Stage ◽  
Aging Process ◽  
Great Increase ◽  
Cube Root ◽  
Cu Alloys ◽  
The Matrix ◽  
The Mean ◽  
Almost All

Aging of Fe-Cu alloys or steels containing copper may result in the formation of the dispersion of nanometric precipitates in the matrix and, thus, causes a great increase in the strength of the alloys. A model is developed describing the aging process of Fe-Cu alloys. The model is first satisfactorily verified by comparing with the reported experimental results, and then applied to calculate the microstructure evolution during aging a Cu-Fe alloy. The numerical results demonstrate that the nucleation of the precipitates occurs after a period of incubation. Since that time on the microstructure evolution is the result of the concurrent action of nucleation, growth/shrinkage and structural transformation of the precipitates. In the late stage of aging almost all the precipitates are of 9R structure. The mean particle radius varies linearly with the cube root of time

Precipitation Phenomena in Implanted Ionic Oxide MgO

1981 ◽  
Vol 7 ◽  
Author(s):  
A. Perez ◽  
M. Treilleux ◽  
P. Thevenard ◽  
G. Abouchacra ◽  
G. Marest ◽  
...  
Keyword(s):  
Rutherford Backscattering Spectrometry ◽  
Spinel Ferrite ◽  
Precipitation Process ◽  
X Ray Diffraction ◽  
Cationic Sublattice ◽  
Alkali Ions ◽  
Transmission Electron ◽  
The Matrix ◽  
Precipitation Phenomena ◽  
Precipitated Phases

ABSTRACTMgO single crystals implanted with alkali ions (Li+, Na+, K+ and Rb+),Fe+, In+ and Au+ ions have been studied after implantation with doses up to 1017 ions.cm−2 and after annealing at temperatures up to 1100°C.In order to characterize defects and precipitated phases, several techniques have been associated depending on the implanted ions : optical absorption, transmission electron microscopy, Rutherford backscattering spectrometry, conversion electron Mössbauer spectroscopy and X-ray diffraction at oblique incidence. Directly after implantation the intrinsic defects in the anionic sublattice (F, F+, F2-centers) and in the cationic sublattice (V−-centers) are observed. As to the implanted species, two precipitation processes are observed : (i) the implanted ions precipitate independently of the matrix elements. This is the case of alkali ions which form alkali metal precipitates. (ii) the implanted species precipitate with those of the matrix to form compounds. This is observed with iron which forms oxide precipitates and spinel ferrite. In the case of indium and gold, the precipitation process occurs with the cations of the matrix to form binary alloys : Mg3In and Au3Mg.

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