Showing 4 results for Semisolid
M. Ghalambaz,, M. Shahmiri, Y. H. K Kharazi,
Volume 4, Issue 1 (6-2007)
Abstract
Abstract: Problems such as the difficulty of the selection of processing parameters and the large
quantity of experimental work exist in the morphological evolutions of Semisolid Metal (SSM)
processing. In order to deal with these existing problems, and to identify the effect of the
processing parameters, (i.e. shearing rate-time-temperature) combinations on particle size and
shape factor, based on experimental investigation, the Artificial Neural Network (ANN) was
applied to predict particle size and shape factor SSM processed Aluminum A.356.0 alloy. The
results clearly demonstrated that, the ANN with 2 hidden layers and topology (4, 2) can predict the
shape factor and the particle size with high accuracy of 94%.The sensivity analysis also revealed
that shear rate and solid fraction had the largest effect on shape factor and particle size,
respectively. The shear rate had a reverse effect on particle size.
M .shahmiri, , H. Arabi ,
Volume 6, Issue 4 (12-2009)
Abstract
Abstract:
The aims of this research were to investigate the effects of semisolid metal (SSM) processing parameters (i.e., shear rates –times – temperatures combinations) on the primary solidification products and isothermal holding duration, subsequent to cessation of stirring on the secondary solidification of Al-Si (A356) alloy.
The dendrite fragmentation was found to be the governing mechanism of the primary dendritic to non-dendritic transformation, via rosette to final pseudo-spherical shapes during the primary solidification
The secondary solidification of the liquid in the slurry was not only a growth phenomenon but also promoted by 1) fresh heterogeneous nucleation and growth of dendrites and 2) the dendritic growth of the primary solidification products in the remaining liquid. Upon cessation of stirring and gradual disappearance of the prior shear force, the slurry relaxed, and the secondary solidification products pertained to conventional solidification condition
M. Shahmiri,
Volume 13, Issue 4 (12-2016)
Abstract
Over the last few decades, there have been many mechanisms proposed to describe the formation of the non-dendritic microstructures during Semisolid Metal (SSM) processing; including dendrite fragmentation, spherical growth, cellular growth and recalescence. Dendrite fragmentation is the most popular mechanism of all these hypotheses. It is the purpose of the present article to examine the morphological evolution of the non-dendritic microstructures, based on models proposed by Flemings, Vogel, Cantor, and Doherty during SSM processing of the Al-Si (A356) alloy. Based on new microstructural evidences, including (1) - plastic deformation at the side arms by slip lines formation as a result of the thermal fatigue mechanism, (2) - crack formation at the root of the side arms and (3) – the interaction of a rapidly sheared hot viscous medium with these regions, i.e. erosion; it propose and hereby discuss a new mechanism called "fatigue –erosion", for dendrites fragmentation of the experimental alloy. Optical and Scanning Electron Microscopy (SEM) with EBSD and EDS, TEM, and AFM was used for the microstructural characterizations.
Mohammad Alipour,
Volume 20, Issue 1 (3-2023)
Abstract
The effect of Strain-Induced Melt-Activated (SIMA) Process, ultrasonic treatment (UST) and Al-5Ti-1B refiner on the microstructure and globularity of Al–15%Mg2Si composite was studied. Deformation of 25% were used. After deformation the samples were heated at 560, 580 and 595 °C for 5, 10, 20 and 40 min. The composite was treated with different amounts of the Ti concentrations and ultrasonic treatment with different power. Microstructural study was carried out on the alloy. It was observed that SIMA process, ultrasonic treatment and Al-5Ti-1B refiner has caused the globular morphology of Mg2Si particles. The results showed that for the desired microstructures of the alloy during SIMA process, the optimum temperature and time are 595 °C and 20 min respectively. Optimum amount of Ti refiner is 1 wt.% and power for UST is 1800W. After applying the SIMA process, Al-5Ti-1B master alloy and ultrasonic treatment, the strength and engagement have increased. This means that tensile strength increases from 251 MPa to 303 MPa and elongation percentage improves from 2.1 to 3.4, respectively.
