Optimization of Particle Size and Distribution by Hydrostatic Extrusion

2007 ◽  
Vol 561-565 ◽  
pp. 869-872 ◽  
Author(s):  
Małgorzata Lewandowska ◽  
Kinga Wawer
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Aluminium Alloys ◽  
Hydrostatic Extrusion ◽  
Nanometer Scale ◽  
Second Phase ◽  
Size Refinement ◽  
Second Phase Particles ◽  
Fatigue And Fracture

Hydrostatic extrusion (HE) as a method of metals forming is known for about 100 years. Recently, it has been utilized as an efficient way of grain size refinement down to nanometer scale. In the case of engineering metals, HE processing alters not only grain size but also second phase particles such as intermetallic inclusions and precipitates. During HE processing, these particles significantly change their size, shape and spatial distribution. These changes are accompanied by improvement in properties of processed metals such as fatigue and fracture toughness. In the present work, changes of second phase particles induced by HE are described in a quantitative way for aluminium alloys. Their impact on mechanical properties is also discussed.

Mechanical Properties of (Al2O3+Ni) and (Al2O3+Ni)/Ni Laminated Materials

2007 ◽  
Vol 353-358 ◽  
pp. 1447-1450
Author(s):  
Kai Hui Zuo ◽  
Dong Liang Jiang ◽  
Qing Ling Lin ◽  
Yu Ping Zeng ◽  
Zhong Ming Chen
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Hot Pressing ◽  
Tape Casting ◽  
Crack Deflection ◽  
Second Phase ◽  
Microstructure Refinement ◽  
Hot Pressing Sintering ◽  
Laminated Materials

(Al2O3+Ni) and (Al2O3+Ni)/Ni laminated materials were prepared by tape casting and hot pressing sintering. The mechanical properties of (Al2O3+20wt%Ni) laminated composites were higher than those of (Al2O3+50wt%Ni) composites and Al2O3 sample. The strengthening in the (Al2O3+Ni) composites mainly results from microstructure refinement of the alumina grain size, cracks bridging and crack deflection by the Ni particles. Results showed that the strength and fracture toughness of (Al2O3+Ni)/Ni laminated materials were higher than those of Al2O3/Ni laminated materials with the same layer numbers and thickness ratio. The good mechanical properties of (Al2O3+Ni) and (Al2O3+Ni)/Ni laminated materials result from the second phase of Ni particles in Al2O3 layers.

Improvement of Mechanical Properties of 7475 Aluminium Alloy by the Combination of SPD Processing and Annealing

2011 ◽  
Vol 690 ◽  
pp. 311-314 ◽  
Author(s):  
Kinga Wawer ◽  
Małgorzata Lewandowska ◽  
Krzysztof Jan Kurzydlowski
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Aluminium Alloy ◽  
True Strain ◽  
Hydrostatic Extrusion ◽  
Synergic Effect ◽  
Size Refinement ◽  
Low Temperature Annealing ◽  
Heat Treated ◽  
Precipitate Strengthening

In the present study, SPD processing was combined with annealing in order to obtain synergic effect of grain size refinement and precipitate strengthening. Samples of 7475 alloy were solution heat treated, water quenched and then subjected to hydrostatic extrusion with a total true strain of about 4. Hydrostatic extrusion resulted in a significant grain refinement from 70 mm to about 70 nm. The samples were subsequently annealed at temperatures inducing the formation of nano-precipitates. The investigations of the structure and mechanical properties of the samples subjected to SPD and annealing revealed different precipitation path in micro- and nano-grained samples. Also, it was found that the combination of HE processing and low temperature annealing results in the formation of nano-precipitates in nano-grained structures which effectively strengthen nano-aluminium alloy.

scholarly journals Effects of Excessive Zr Content and Ultrasonic Treatment on Microstructure and Mechanical Properties of Al-Zn-Mg-Cu Alloy

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 632
Author(s):  
Cheng Li ◽  
Shusen Wu ◽  
Shulin Lü ◽  
Jianyu Li ◽  
Longfei Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Ultrasonic Vibration ◽  
Ultrasonic Treatment ◽  
Second Phase ◽  
Cu Alloy ◽  
Cu Alloys ◽  
Microstructure And Mechanical Properties ◽  
Second Phase Particles ◽  
Properties Of Materials

The Zr element is one of the important grain refiners for 7xxx series Al-Zn-Mg-Cu alloys, but the effect of Zr content more than 0.15 wt.% needs to be deeply investigated under the action of ultrasonic vibration. In this study, the effects of Zr contents (0.1 to 0.25 wt.%) on microstructure and mechanical properties of Al-Zn-Mg-Cu alloy were studied. The results showed that Zr element could refine grains, but when the Zr content was greater than 0.15 wt.%, the grain size was not uniform, the number of second phase particles increased, and the segregation of components became more serious. It was found that after ultrasonic treatment, the grain-size inhomogeneity was greatly improved, and the Zr content could be added up to 0.2 wt.%. When the Zr content is equal or lower than 0.2 wt.%, ultrasonic treatment can effectively improve the mechanical properties of materials by refining grains and weakening segregation. However, when the Zr content is up to 0.25 wt.%, the effect is getting worse.

Effect of Second Phase on the Mechanical Properties of Mg-Al-Zn Alloy by Equal Channel Angular Extrusion

2007 ◽  
Vol 546-549 ◽  
pp. 249-252 ◽  
Author(s):  
Wen Jiang Ding ◽  
Li Jin ◽  
Dong Liang Lin ◽  
Xiao Qin Zeng ◽  
Da Li Mao
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Magnesium Alloy ◽  
Equal Channel Angular Extrusion ◽  
Tensile Deformation ◽  
Second Phase ◽  
Second Phase Particles ◽  
Angular Extrusion ◽  
Zn Alloy ◽  
Zn Alloys

The effect of second phase on the mechanical properties of AZ61 and AZ91 Mg-Al-Zn magnesium alloy processed by equal-channel angular extrusion (ECAE) has been investigated. The results revealed that cracks initiated at and propagated through the α-Mg/β-Mg17Al12 interfaces and grain boundaries of Mg-Al-Zn alloys during tensile deformation. For AZ61, the elongation increased with the increase of ECAE pass number and the decrease of grain size. However, the elongation of AZ91 with more second phase particles decreased with the increase of ECAE pass number and the decrease of grain size.

Particle Redistribution and Grain Refinement during Processing by Hydrostatic Extrusion

2008 ◽  
Vol 584-586 ◽  
pp. 541-546 ◽  
Author(s):  
Kinga Wawer ◽  
Małgorzata Lewandowska ◽  
Krzysztof Jan Kurzydlowski
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Grain Refinement ◽  
Hydrostatic Extrusion ◽  
Strength Increase ◽  
Two Phase ◽  
Size Refinement ◽  
Cast Alloys ◽  
Tensile Strength Increase

In this study particle redistribution and grain size refinement induced by hydrostatic extrusion (HE) have been studied in two Al-Si cast alloys (Al-9%Si and Al-11%Si). It has been found that HE results in a significant changes in particle shape, size and distribution which was revealed by SEM observations and quantified using stereological parameters. At the same time, significant grain refinement down to ~100 nm in diameter takes place in aluminium phase. Such a microstructure evolution affects substantially the mechanical properties of two-phase alloys. The yield strength and tensile strength increase over two times whereas the plasticity only slightly decreases.

Dependence of fracture toughness on multiscale second phase particles in high strength Al alloys

2003 ◽  
Vol 19 (7) ◽  
pp. 887-896 ◽  
Author(s):  
G. Liu ◽  
G.-J. Zhang ◽  
X.-D. Ding ◽  
J. Sun ◽  
K.-H. Chen
Keyword(s):  
Fracture Toughness ◽  
High Strength ◽  
Al Alloys ◽  
Second Phase ◽  
Second Phase Particles

Internal Stresses in Nanocrystalline Nickel and Nickel-Iron Alloys

2012 ◽  
Vol 706-709 ◽  
pp. 1607-1611 ◽  
Author(s):  
J.D. Giallonardo ◽  
Uwe Erb ◽  
G. Palumbo ◽  
G.A. Botton ◽  
C. Andrei
Keyword(s):  
Grain Size ◽  
Internal Stress ◽  
Structural Difference ◽  
Intrinsic Stress ◽  
Internal Stresses ◽  
Second Phase ◽  
Nickel Iron ◽  
Second Phase Particles ◽  
Second Phases ◽  
Rule Out

Nanocrystalline metals are often produced in a state of stress which can adversely affect certain properties, e.g. corrosion resistance, wear, fatigue strength, etc. This stress is referred to as internal or “intrinsic” stress since it is not directly caused by applied loads. The structural causes of these stresses in nanocrystalline materials are not fully understood and are therefore an area of particular interest. The internal stresses of nanocrystalline Ni and Ni-16wt%Fe were measured and found to increase with the addition of iron. Characterization using HR-TEM revealed no signs of porosity, second phase particles, or a high density of dislocations. Both materials possessed well defined high-angle grain boundaries. The main structural difference between the two materials was found to be grain size and correspondingly, a decrease in grain size resulted in an increase in internal stress which supports the applicability of the coalescence theory. The current study also provides evidence to rule out the effect of voids (or porosity), dislocations, and second phases as possible causes of internal stress.

The second phase particles and mechanical properties of 2124 aluminum alloy processed by accumulative back extrusion

2014 ◽  
Vol 58 ◽  
pp. 535-542 ◽  
Author(s):  
P. Shaterani ◽  
A. Zarei-Hanzaki ◽  
S.M. Fatemi-Varzaneh ◽  
S.B. Hassas-Irani
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Second Phase ◽  
Second Phase Particles

Influence of Severe Plastic Deformation on the PLC Effect and Mechanical Properties in Al 5XXX Alloy

2006 ◽  
Vol 114 ◽  
pp. 171-176 ◽  
Author(s):  
Joanna Zdunek ◽  
Pawel Widlicki ◽  
Halina Garbacz ◽  
Jaroslaw Mizera ◽  
Krzysztof Jan Kurzydlowski
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Grain Size ◽  
Severe Plastic Deformation ◽  
True Strain ◽  
Tensile Tests ◽  
Size Reduction ◽  
Hydrostatic Extrusion ◽  
Stress Strain ◽  
Chatelier Effect

In this work, Al-Mg-Mn-Si alloy (5483) in the as-received and severe plastically deformed states was used. Plastic deformation was carried out by hydrostatic extrusion, and three different true strain values were applied 1.4, 2.8 and 3.8. All specimens were subjected to tensile tests and microhardness measurements. The investigated material revealed an instability during plastic deformation in the form of serration on the stress-strain curves, the so called Portevin-Le Chatelier effect It was shown that grain size reduction effected the character of the instability.

The Use of Bobbin Tools for Friction Stir Welding of Aluminium Alloys

2010 ◽  
Vol 638-642 ◽  
pp. 1179-1184 ◽  
Author(s):  
Philip L. Threadgill ◽  
M.M.Z. Ahmed ◽  
Jonathan P. Martin ◽  
Jonathan G. Perrett ◽  
Bradley P. Wynne
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Friction Stir Welding ◽  
Cross Section ◽  
Axial Force ◽  
Aluminium Alloys ◽  
Processing Parameters ◽  
Machine Design ◽  
Friction Stir ◽  
Triangular Zone

The use of a double sided friction stir welding tool (known as a bobbin tool) has the advantage of giving a processed zone in the workpiece which is more or less rectangular in cross section, as opposed the triangular zone which is more typically found when conventional friction stir welding tool designs are used. In addition, the net axial force on the workpiece is almost zero, which has significant beneficial implications in machine design and cost. However, the response of these tools in generating fine microstructures in the nugget area has not been established. The paper presents detailed metallographic analyses of microstructures produced in 25mm AA6082-T6 aluminium wrought alloy, and examines grain size, texture and mechanical properties as a function of processing parameters and tool design, and offers comparison with data from welds made with conventional tools.

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