Study on Semi-Solid Magnesium Alloy Produced by Mechanical Stirring

2010 ◽  
Vol 146-147 ◽  
pp. 1723-1728
Author(s):  
Bing Feng Zhou ◽  
Hong Yan
Keyword(s):  
Magnesium Alloy ◽  
Cooling Rate ◽  
Dendritic Structure ◽  
Spherical Particles ◽  
Solid Alloy ◽  
Mechanical Stirring ◽  
Stirring Rate ◽  
Stirring Time ◽  
Semi Solid ◽  
Spherical Grains

Semi-solid magnesium alloy slurry was produced by a newly self-developed mechanical stirring machine in order to prepare continuous semi-solid slurry. The changing principle of semi-solid microstructure was studied under different conditions—the changing of temperature, stirring rate, cooling rate and stirring time. It was showed that the lower the temperature of slurry, the higher the stirring rate, the longer the stirring time and the faster the cooling rate, the grain will be smaller and more evenly rounded. When the stirring speed and temperature are the same, better semi-solid spherical grains can be gained by increasing the stirring time. At the same stirring temperature and higher stirring speed, semi-solid spherical particles are smaller, rounder and more evenly; at a low stirring speed, we can't get ideal semi-solid spherical grains even if we increase the stirring time. The ideal technological parameters of semi-solid AZ61 alloy produced with no-dendritic structure were recommended to be 600°C～605°C (stirring end temperature) 、3min～ 5min(stirring time) and 500r/min(stirring rate). Compared with conventional casting alloy, semi-solid alloy mechanical properties were greatly improved. The non-dendrite semi-solid forming mechanism was studied; mechanical stirring semi-solid non-dendritic formation was the result of a variety of factors, the key cause is mechanical shear stress.

Effect of Disturbing Conditions in Semi-Solid State on Microstructure Evolution of Magnesium Alloy

2006 ◽  
Vol 116-117 ◽  
pp. 296-299 ◽  
Author(s):  
Hong Jin Zhao ◽  
Yong Lin Kang ◽  
Zhao Hui Wang ◽  
Hai Liang Du
Keyword(s):  
Solid State ◽  
Magnesium Alloy ◽  
Microstructure Evolution ◽  
High Efficiency ◽  
External Disturbance ◽  
Dendritic Structure ◽  
Good Effect ◽  
Mechanical Stirring ◽  
Β Phase ◽  
Semi Solid

In this paper the microstructure evolution of AZ91HP magnesium alloy casts produced under different disturbing treatment conditions such as non-disturbing, argon blowing and mechanical stirring in semi-solid state after holding a short time was studied. The results show that the grains of AZ91HP alloy casts refined, the secondary dendritic arms grown and the dendrites tend to rosette shape with the decrease of holding temperature. External disturbance can accelerate the evolution process, and the spherical primary α phase formed easily under mechanical stirring treatment condition. The formation of non-dendritic structure is owing to ripening of the dendritic arms, refinement of the grains and movement of the primary formed solid phases. Disturbing treatments in semi-solid state induce more equilibrium solidification and decrease the amount of brittle β-Mg17Al12 phase. Blowing argon into the refined and modified magnesium alloy in semi-solid state can obtain homogeneous non-dendritic structure and the net shaped β phase distributed on α-Mg phase boundaries become fine and thin, this may be have a good effect on the mechanical properties of the magnesium alloy casts. Due to the low disturbing strength, argon blowing can maintain the metallurgy quality of the semi-solid slurry well, and also have high efficiency to make it. This technology need not new complex equipments and can be practiced in conventional casting conditions, so it may be used in industrialize manufacture.

Research on Semi-Solid Y112 Alloy Fabricated by Mechanical Stirring

2010 ◽  
Vol 139-141 ◽  
pp. 657-660
Author(s):  
Hong Yan ◽  
Yong Hu
Keyword(s):  
Tensile Strength ◽  
Technological Parameters ◽  
Mechanical Stirring ◽  
Stirring Time ◽  
Semi Solid ◽  
Spherical Grains

Effects of different technological parameters such as stirring temperature, stirring speed and stirring time on the microstructure of semi-solid Y112 alloy were investigated using a self-developed mechanical stirring device in this paper. The results show that the higher of stirring temperature and stirring speed, the finer and more homogeneous the spherical grains, the higher the tensile strength and elongation. If the temperature is too high, the solid grains will be melted, the tensile strength and elongation will be reduced. With the increasing of stirring time, the grains firstly become fine, uniform and round, and then grow up. The tensile strength and elongation firstly increase, and then reduce.

Effects of Technological Parameters on Microstructures of Semi-Solid Magnesium Matrix Composites

2010 ◽  
Vol 97-101 ◽  
pp. 1607-1610
Author(s):  
Yong Hu ◽  
Shu Zhen Li ◽  
Bo Lin He ◽  
Hong Yan
Keyword(s):  
Chinese Script ◽  
Matrix Composites ◽  
Technological Parameters ◽  
Magnesium Matrix ◽  
Magnesium Matrix Composites ◽  
Mechanical Stirring ◽  
Stirring Time ◽  
Semi Solid ◽  
Spherical Grains

Mg2Si/AM60 composites were fabricated by in-situ synthesis and the effects of different stirring technological parameters on the microstructures of semi-solid magnesium matrix composites were investigated in this paper. The results indicated that there were Chinese script type Mg2Si particles in the microstructures by addition crystal Si to the magnesium alloys. The mechanical stirring was used to fabricate the semi-solid composites and the results showed that the higher the stirring temperature and speed are, the finer and more homogeneous the spherical grains would be. If the temperature is too high, the grains will be melted. With the increasing of stirring time, the grains become fine, well-distributed and round at first, then grow up.

Microstructure and Mechanical Properties of Sn-Bi Alloy Treated in the Semi-Solid State by Mechanical Stirring Process

2010 ◽  
Vol 150-151 ◽  
pp. 1768-1771 ◽  
Author(s):  
Feng Li ◽  
Yong Jun Hu ◽  
Xiao Ling Cheng ◽  
Xiao Ting Xiao
Keyword(s):  
Mechanical Properties ◽  
Solid State ◽  
Die Casting ◽  
Percentage Elongation ◽  
Mechanical Stirring ◽  
Microstructure And Mechanical Properties ◽  
Stirring Time ◽  
Microstructures And Mechanical Properties ◽  
Semi Solid

In this work, the effect of stirring time on the solidifed microstructures and mechanical properties of semi-solid Sn-Bi slurry was investigated by the mechanical stirring method. The results indicated that a fine round granular solidifed structure of Sn-Bi semi-solid slurry was obtained at 142 and stirred for 8 min. Compared with the Sn-Bi alloy prepared conventional die casting, the mechamical properties of semi-solid Sn-Bi alloy was improved prominently. The percentage elongation of semi-solid Sn-Bi alloy was increased 67 % compared with that of the Sn-Bi alloy prepared conventional die casting.

Simplified Rheocasting of Al-Si Alloys Sheared by Mechanical Stirring

2015 ◽  
Vol 651-653 ◽  
pp. 1545-1550 ◽  
Author(s):  
Alfredo Hernández ◽  
J. Federico Chávez ◽  
Raquel E. Hernández
Keyword(s):  
Stainless Steel ◽  
Solid State ◽  
Shear Rate ◽  
Microstructural Characterization ◽  
Dendritic Morphology ◽  
Solid Alloy ◽  
Mechanical Stirring ◽  
Simplified Method ◽  
Thixotropic Behavior ◽  
Semi Solid

A rheocasting prototype for the semi-solid processing of Al-Si alloys was designed and assembled at laboratory scale, this is the first attempt for the development of S2P equipment in Mexico. This work describes the simplified method of mechanical stirring and the calculation of the theoretical parameters for the operation of the experimental device in order to provide shear rate into the slurry by a stainless steel impeller inside a crucible made of hot work steel. Moreover, a vertical pressure die-rheocasting system it is applied with the semi-solid alloy flowing counter the position of the injector during the displacement of the crucible in order to fill the mold. New design is applied in this rheocasting equipment.The semi-solid state with thixotropic behavior is produced in the stirred AlSi7Mg alloy; this condition allows the non-dendritic morphology because the intensively stirring at the beginning of the solidification produces the trimming of dendrites, growing so the primary solid (α) in globular shape surrounded by eutectic microstructure. Preliminary microstructural characterization was performed.

Microstructure Evolution during Semi-Solid Processing of SCN-Water and Sn-Pb Alloys

2006 ◽  
Vol 116-117 ◽  
pp. 437-440
Author(s):  
Tao Li ◽  
Xin Lin ◽  
Wei Dong Huang
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Microstructure Evolution ◽  
In Situ Observation ◽  
Cooling Process ◽  
Mechanical Stirring ◽  
Stirring Rate ◽  
Single Grain ◽  
Semi Solid

Microstructure evolution was investigated during the solidification of succinonitrile-5at.% water transparent alloy and Sn–15 wt.%Pb alloy under mechanical stirring through in-situ observation and quenching, separately. The results showed that the evolution of primary microstructures under stirring experienced the growth of single grain particle and the successive agglomerating and coarsening of multi-particles when the particle size reached a certain value. The increase of stirring rate promoted the globular growth of solidification microstructure after it nucleated in the melt and increase the grain size. Thus, the microstructure during semi-solid processing could be refined by a controlled stirring and cooling process, which depended on the optimization among the stirring rate, cooling rate and temperature at which the stirring rate is changed.

Research on the Self-Thickening Effects in the Process of Fabricating Aluminum Foam Using Semi-Solid Melt by Mechanical Stirring

2011 ◽  
Vol 675-677 ◽  
pp. 633-637
Author(s):  
Nan Li ◽  
Shu Ming Xing ◽  
Pei Wei Bao ◽  
Zhi Min Liu
Keyword(s):  
Solid Fraction ◽  
Aluminum Foam ◽  
Metal Foam ◽  
High Viscosity ◽  
Solid Particles ◽  
The Self ◽  
Mechanical Stirring ◽  
Blowing Agents ◽  
Stirring Time ◽  
Semi Solid

This paper investigated the self-thickening effects on fabricating close cell aluminum foam directly using semi-solid melt by mechanical stirring without adding other particles. Using the high viscosity character of semi-solid melt as well as mechanical stirring technique, blowing agents (TiH2) could be homogeneously distributed without other thickening additions such as CaO or TiC which were commonly used to thicken aluminum melt in metal foam industry. It was observed that the semi-solid melt could reach a proper condition for the blowing agents to separate and foam after self-thickening process and the solid fraction played a key role in self-thicken effects compared to the stirring time and speed. The self-thickening effects could meet the purity requirement of melt as well as to fabricate aluminum foam with small pores and good structure using precursors. Aluminum foam was a multi-functional material with features of ultra-light, high-toughness, impact resistance, high specific strength, high specific stiffness, heat isolation and fire retardant [1]. The viscosity of melt was extremely important in the process of fabricating aluminum foam. Jin.I and Kenny.LD did some research on the effects of adding solid particles to thicken the melt and their study showed that the best thickening effect could be obtained when the particle size of 5-20 mm and the proportion of 10~20% of liquid aluminum [2]. Miyoshi.T also did some research on the stirring time in the thickening process and showed that adding Ca particles of 1.5~3%(wt) could effectively controlled the viscosity [2]. Research by J.Banhart showed shat 1-5 %(wt) Al2O3 and SiC adding particles could also thicken the semi-solid melt very effectively[3] [4]. Berry.CB and Hall.CG’s research showed that blowing air, oxygen or other gases could also reach thickening effect [2]. There were several methods to thicken the melt but the same ultimate goal was to obtain a suitable melt environment for distribution and foaming of blowing agents. This paper mainly investigated the effects of the self-thickening semi-solid melt on the distribution behavior of blowing agents. Taking the advantage of the high viscosity of semi-solid melt as well as mechanical stirring technique, without adding other thickening particles, blowing agents (TiH2) could be homogeneously distributed in the semi-solid melt. The parameters such as solid fraction, stirring time and speed were investigated in this paper.

Influence of Processing Parameters on Microstructure of Casting Rolling Semi-Solid AZ91D Magnesium Alloy

2008 ◽  
Vol 141-143 ◽  
pp. 535-538 ◽  
Author(s):  
Ying Zhang ◽  
Mao Peng Geng ◽  
Lei Cheng ◽  
Yan Chun Wang
Keyword(s):  
Great Influence ◽  
Processing Parameters ◽  
Casting Temperature ◽  
Technological Parameters ◽  
Standing Time ◽  
Mechanical Stirring ◽  
Az91d Magnesium Alloy ◽  
Stirring Time ◽  
Semi Solid ◽  
Evolution Of Microstructure

Semi-solid AZ91D magnesium slurry was prepared by mechanical stirring method and the evolution of microstructure under different technological parameters such as casting temperature, standing time, stirring time and stirring speed et al were studied. The results show that the technological parameters have great influence on the microstructure of the semi-solid magnesium slurry. Neither too high nor too low stirring speed is a benefit to form the semi-solid state; stirring time is also not too long; higher casting temperature is unfavorable; with the increasing of standing time, the steady-state apparent viscosity of the slurry increases rapidly, the number of nucleation increases and the crystalline structure becomes finer.

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