scholarly journals Modelling of Precipitation Hardening in Casting Aluminium Alloys

2009 ◽  
Vol 618-619 ◽  
pp. 203-206 ◽  
Author(s):  
Linda Wu ◽  
W. George Ferguson
Keyword(s):  
Particle Size ◽  
Aluminium Alloys ◽  
Room Temperature ◽  
Precipitation Hardening ◽  
Numerical Approach ◽  
Precipitation Process ◽  
Dislocation Theory ◽  
Strength Model ◽  
Aging Hardening ◽  
Nucleation Growth

Precipitation hardening, or aging hardening, is one of the most widely adopted techniques for strengthening of aluminium alloys. During the precipitation process, three major mechanisms are involved: i.e. nucleation, growth and coarsening. Kampmann and Wagner have developed a powerful and flexible numerical approach (KWN model) for dealing with concomitant nucleation, growth and coarsening and thus capable of predicting the full evolution of the particle size distribution. KWN model has been successfully applied to a number of aluminium alloy systems, such as 2xxx, 6xxx and 7xxx. However, most of these modelling works were focused on the wrought aluminium alloys, few had applied to the casting aluminium alloys. In the present modelling work, the microstructure evolution is modeled based on the KWN model and then a strength model based on the well established dislocation theory is used to evaluate the resulting change in hardness or yield strength at room temperature. Then the modelling is applied to casting aluminium alloys A356 and A357. And the modelling results are validated by comparing with own experimental results and the results obtained from the open literature.

SYNTHESIS AND MORPHOLOGICAL CONTROL OF MONODISPERSED MICROSIZED CERIA PARTICLES

2010 ◽  
Vol 17 (02) ◽  
pp. 147-152 ◽  
Author(s):  
S. YIN ◽  
Y. MINAMIDATE ◽  
T. SATO
Keyword(s):  
Particle Size ◽  
Cerium Oxide ◽  
Room Temperature ◽  
Aging Treatment ◽  
Precipitation Process ◽  
Homogeneous Precipitation ◽  
Morphological Control ◽  
Oxide Particles ◽  
Cerium Carbonate ◽  
Carbonate Precursor

The morphological control of crystalline cerium oxide particles was realized by homogeneous precipitation process followed by calcination in air at 400°C. The effects of room temperature pre-aging time on the morphologies of final products were investigated. Monodispersed rod-like cerium carbonate precursor was produced at 70°C for 2 h using the solution without pre-aging treatment. In contrast, monodispersed spherical precursor and plate-like precursor were obtained under the same conditions after pre-aging the solution at 25°C for 72 and 144 h, respectively. Ceria particles with similar morphologies and particle size to those of carbonate precursor could be obtained after calcination in air at 400°C. The monodispersed spherical, rod-like, and plate-like cerium oxide particles were successfully synthesized.

scholarly journals Design and Optimization of the Local Laser Treatment to Improve the Formability of Age Hardenable Aluminium Alloys

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1576 ◽  
Author(s):  
Antonio Piccininni ◽  
Gianfranco Palumbo
Keyword(s):  
Laser Treatment ◽  
Deep Drawing ◽  
Aluminium Alloys ◽  
Room Temperature ◽  
Physical Simulation ◽  
Experimental Tests ◽  
Numerical Approach ◽  
Drawing Ratio ◽  
Design And Optimization ◽  
Local Modification

The research of innovative methodologies to improve the Aluminium alloys formability at room temperature still remains an open question: the local modification of the material properties via short-term heat treatments followed by the stamping at room temperature is reported to be an effective alternative to the forming in warm conditions. In the present work, such a methodology has been applied to the deep drawing of an age-hardenable Aluminium alloy (AA6082-T6) using an experimental/numerical approach. A preliminary extensive material characterization was aimed at investigating the material behaviour: (i) in the as-received condition (peak hardening), (ii) in the supersaturated condition (obtained by physical simulation) and (iii) after being locally solutioned via laser heating. A Finite Element based approach (Abaqus CAE, v. 6.17) was then used to design the laser treatment of the blanks to be subsequently deep drawn at room temperature: a 2D axisymmetric model of the deep drawing process was coupled with the optimization platform modeFRONTIER in order to define the radial extent of the laser heat treated area able to maximize the Limit Drawing Ratio. The experimental tests were finally conducted for validation purposes and revealed the effectiveness of the adopted approach which allowed to improve the drawability of more than 20% with respect to the as received condition (T6).

scholarly journals A numerical approach for the modelling of forming limits in hot incremental forming of AZ31 magnesium alloy

2021 ◽  
Author(s):  
Davide Campanella ◽  
Gianluca Buffa ◽  
Ernesto Lo Valvo ◽  
Livan Fratini
Keyword(s):  
Room Temperature ◽  
Incremental Forming ◽  
Material Model ◽  
Numerical Approach ◽  
Forming Limit ◽  
Material Strength ◽  
Wall Angle ◽  
Analytical Expression ◽  
The Poor ◽  
Specific Material

AbstractMagnesium alloys, because of their good specific material strength, can be considered attractive by different industry fields, as the aerospace and the automotive one. However, their use is limited by the poor formability at room temperature. In this research, a numerical approach is proposed in order to determine an analytical expression of material formability in hot incremental forming processes. The numerical model was developed using the commercial software ABAQUS/Explicit. The Johnson-Cook material model was used, and the model was validated through experimental measurements carried out using the ARAMIS system. Different geometries were considered with temperature varying in a range of 25–400 °C and wall angle in a range of 35–60°. An analytical expression of the fracture forming limit, as a function of temperature, was established and finally tested with a different geometry in order to assess the validity.

Effect of Equal-Channel Angular Pressing (ECAP) on Creep in Aluminium Alloys

2007 ◽  
Vol 539-543 ◽  
pp. 2904-2909 ◽  
Author(s):  
Vàclav Sklenička ◽  
Jiří Dvořák ◽  
Marie Kvapilová ◽  
Milan Svoboda ◽  
Petr Král ◽  
...  
Keyword(s):  
Equal Channel Angular Pressing ◽  
Aluminium Alloys ◽  
Creep Resistance ◽  
Room Temperature ◽  
Creep Behaviour ◽  
Coarse Grained ◽  
Pure Aluminium ◽  
Creep Tests ◽  
Angular Pressing ◽  
Compression Creep

This paper examines the effect of equal-channel angular pressing (ECAP) on creep behaviour of pure aluminium, binary Al-0.2wt.%Sc alloy and ternary Al-3wt.%Mg-0.2wt.%Sc alloy. The ECAP was conducted at room temperature with a die that had a 90° angle between the channels and 8 repetitive ECAP passes followed route BC. Constant stress compression creep tests were performed at 473 K and stresses ranging between 16 to 80 MPa on ECAP materials and, for comparison purposes, on the initial coarse-grained materials. The results showed that the creep resistance of the ECAP processed Al-Sc and Al-Mg-Sc alloys was markedly deteriorated with respect to unpressed coarse-grained materials.

Modification in Texture of Magnesium by the Addition of Rare Earth Elements and its Influence on Mechanical Properties

2012 ◽  
Vol 736 ◽  
pp. 307-315 ◽  
Author(s):  
Murugavel Suresh ◽  
Satyam Suwas
Keyword(s):  
Mechanical Properties ◽  
Rare Earth ◽  
Magnesium Alloys ◽  
Aluminium Alloys ◽  
Room Temperature ◽  
Main Obstacle ◽  
Rare Earth Addition ◽  
Structural Applications ◽  
Re Elements ◽  
The Relationship

Mg alloys show limited room temperature formability compared to its lightweight counterpart aluminium alloys, which is a main obstacle in using this metal for most of the structural applications. However, it is known that grain refinement and texture control are the two possibilities for the improvement of formability of magnesium alloys. Amongst the approaches attempted for the texture weakening, additions through of rare-earth (RE) elements have been found most effective. The relationship between the texture and ductility is well established. In this paper, the effect of rare earth addition on texture weakening has been summarized for various magnesium alloys under the two most common modes of deformation methods.

Sintering of Silver Nanoparticles at Room-Temperature for Conductive Ink Applications

2018 ◽  
Vol 775 ◽  
pp. 144-148 ◽  
Author(s):  
Bethel Faith Y. Rezaga ◽  
Mary Donnabelle L. Balela
Keyword(s):  
Particle Size ◽  
Ag Nanoparticles ◽  
Room Temperature ◽  
Average Diameter ◽  
Aqueous System ◽  
Ag Nanoparticle ◽  
Nacl Solution ◽  
Cellulose Acetate Film ◽  
Sintered Ag ◽  
Nanoparticle Ink

Silver (Ag) nanoparticles synthesized in an aqueous system was sintered at room temperature using NaCl solution. The Ag nanoparticles have an average diameter of about 24 nm. After dispersing the Ag nanoparticles in 50mM NaCl solution, a significant increase in particle size to about 206 nm was observed. On the other hand, the particle size was also increased to about 175 nm when the Ag nanoparticles were printed and then 50mM NaCl solution was dropped onto the printed Ag nanoparticles. The enlargement of particle size was accompanied by the increase in conductivity of the Ag nanoparticle ink. The resistance was reduced from 57.7 to 6.5 and 6.7 ohms for the as-prepared and sintered Ag nanoparticles using two different treatments, respectively. The sintered Ag nanoparticle ink formulation exhibit high conductivity when drawn on both cellulose acetate film and bond paper even after bending and folding of the substrates.

NANOEMULSIONS BASED ON LIPOIC ACID DERIVATIVES WITH VARIOUS ALCOHOLS: PRODUCTION AND INFLUENCE ON FUNCTIONAL ACTIVITY OF PLATELETS

2020 ◽  
pp. 461-464
Author(s):  
A. Sinebryukhova ◽  
A. Shipelova ◽  
E. Darnotuk ◽  
A. Chekanov ◽  
O. Baranova ◽  
...  
Keyword(s):  
Particle Size ◽  
Arachidonic Acid ◽  
Lipoic Acid ◽  
Encapsulation Efficiency ◽  
Room Temperature ◽  
Optimal Conditions ◽  
Pluronic F68 ◽  
Long Term Storage ◽  
Term Storage

The optimal conditions were selected for obtaining homogeneous nanoemulsions (NE) of lipoic acid conjugates (LA-conjugates) based on Pluronic F68 (1,8%) with a particle size not exceeding 400 nm, characterized by 97±2% encapsulation efficiency of substances in nanoparticles (NP). A heterogeneous NE (polydispersity index, PDI>0,3) with the derivative of LA and myo-inositol based on phosphatidylcholine (PC, C = 3 mg/ml) was also obtained consisting of 2 particle fractions: 20–70 nm (27%) and 122–212 nm (73%). The obtained NEs with LA-conjugates based on Pluronic F68 and PC were stable during long-term storage (more than 12 months) at room temperature. The effect of the obtained NEs of LA-conjugates on platelet aggregation (Pt) caused by arachidonic acid (AA) was determined, and a mechanism of their action was proposed.

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