Microstructure evolution and semi-solid deformation behavior of an A356 aluminum alloy processed by strain induced melt activated method

The effects of annulus gap width, stirring power and stirring frequency on the microstructure of the semi-solid A356 aluminum alloy slurry have been investigated by the annulus electromagnetic stirring (AEMS) technology The results show that narrow annulus gap , strong stirring power and high stirring frequency are advantageous to obtain the small spherical primarymicrostructure, the smaller the annulus gap width is, the bigger the stirring power is, and the higher the stirring frequency is, the more uniform, the smaller and the more spherical the microstructure is. So the high stirring frequency, narrow annulus gap, strong stirring power are beneficial to obtain the fine and spherical semisolid microstructure in AEMS. Also the results indicate that the primary particles are globular, small and distribute homogeneously in the AEMS.

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Visualization of Micro-Segregations in A356 Aluminum Alloy by a Color Etching Method

Materials Science Forum ◽

10.4028/www.scientific.net/msf.794-796.9 ◽

2014 ◽

Vol 794-796 ◽

pp. 9-14

Author(s):

Li Gao ◽

Yohei Harada ◽

Shinji Kumai

Keyword(s):

Aluminum Alloy ◽

Grain Growth ◽

Solid Phase ◽

Color Difference ◽

Water Quenching ◽

A356 Aluminum Alloy ◽

Dendritic Microstructure ◽

Spheroidal Microstructure ◽

A356 Aluminum ◽

Semi Solid

An A356 aluminum alloy billet which has a dendritic microstructure was compressed and then partially re-melted to semi-solid state before water quenching, by which the spheroidization of Al grains was realized. A color etchant called Weck's reagent was used to characterize both the dendritic and spheroidal microstructure. In both cases, distinct color differences were observed inside Al grains by normal optical microscopy. Interestingly, a dendritic-shaped structure inside the spheroidal Al grains was visualized, which should be the reflection of the original dendrite before heating and partial re-melting. Also, the grain growth during water quenching could be clearly visualized after etching with this reagent. As a result, solid fractions could be evaluated more precisely by excluding the grain growth when measuring the area of solid phase in 2-D micrographs. In order to investigate the coloring mechanism, electron probe micro-analyses were carried out to characterize the micro-segregations inside an Al grain. Results showed that the micro-segregation of Ti had a strong correlation with the color difference. Detailed investigation found that the micro-segregation of Ti could be preserved after heating and partial re-melting due to the extremely low diffusion rate of Ti in Al.

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Study on Microstructures and Mechanical Properties of Rheo-Die Casting Semi-Solid A356 Aluminum Alloy

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.116-117.453 ◽

2006 ◽

Vol 116-117 ◽

pp. 453-456 ◽

Cited By ~ 1

Author(s):

Yong Lin Kang ◽

Yue Xu ◽

Zhao Hui Wang

Keyword(s):

Mechanical Properties ◽

Aluminum Alloy ◽

Die Casting ◽

A356 Alloy ◽

Experimental Results ◽

A356 Aluminum Alloy ◽

Microstructures And Mechanical Properties ◽

A356 Aluminum ◽

Semi Solid

In this paper, with a newly self-developed rotating barrel rheomoulding machine(RBRM), microstructures and mechanical properties of rheo-die casting A356 alloy were studied. In order to clearly show the characteristic of rheo-die casting, liquid die casting and semi-solid casting were done too. The experimental results showed that microstructures of rheo-die casting were composed of solid grains, which were finer and rounder, and had fewer pores. In the three technologies, integrated mechanical properties of semi-solid rheo-die casting were the best.

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Effect of Experimental Conditions on 7075 Aluminium Response during Thixoextrusion

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.504-506.345 ◽

2012 ◽

Vol 504-506 ◽

pp. 345-350 ◽

Cited By ~ 3

Author(s):

Adriana Neag ◽

Véronique Favier ◽

Mariana Pop ◽

Eric Becker ◽

Régis Bigot

Keyword(s):

Aluminum Alloy ◽

Microstructure Evolution ◽

Deformation Behavior ◽

Liquid Fraction ◽

Heat Losses ◽

Heating Process ◽

Semisolid State ◽

Experimental Conditions ◽

Solid Aluminum ◽

Semi Solid

The deformation behavior of semi-solid aluminum alloy is strongly dependent on the microstructure. This paper illustrates several experimental research works concerning thixoextrusion of 7075 aluminum alloy which was carried out at “Arts et Métiers ParisTech” of Metz. Inductive re-heating of the aluminum billet is the method used in order to obtain the target liquid fraction for thixoextrusion. To minimize the heat losses, a sample obtained from a direct extruded bar is inserted in a die for reheating in semisolid state and thixoextrusion. During the experimental re-heating process, the temperature was directly controlled by using thermocouples for temperature measurements in the sample and also in the die. The influence of different working ram speeds and reheating temperature on the microstructure evolution was studied by optical microscopy. The experimental results on extrusion load and microstructure evolution of the component are reported.

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Influence of Morphology on the Rheological Behavior of Semi-Solid A356 Aluminum Alloy

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.116-117.601 ◽

2006 ◽

Vol 116-117 ◽

pp. 601-605

Author(s):

Heng Hua Zhang ◽

Xian Nian Zhang ◽

Guang Jie Shao ◽

Luo Ping Xu ◽

Yi Tao Yang ◽

...

Keyword(s):

Aluminum Alloy ◽

Solid State ◽

Rheological Behavior ◽

Apparent Viscosity ◽

Flow Behavior ◽

A356 Alloy ◽

Solid Alloy ◽

A356 Aluminum Alloy ◽

A356 Aluminum ◽

Semi Solid

The morphology of semi-solid alloy is one of the key influence factors on the rheological behavior of slurry during die filling and the mechanical properties of formed parts. However, it is difficult to study such effect due to hard controlling of morphology in semi-solid state. In this paper, a self-developed Searle-type viscometer was used to determine the rheological behavior of A356 aluminum alloy in different morphology, which was refined with the salts mixture of K2TiF6 and KBF4. The results indicated that the flow behavior of refined A356 alloy in the semi-solid state possesses obviously thixotropic behavior under isothermal shearing condition with less time to reach steady state and lower steady apparent viscosity as compared to that of the A356 alloy. During continuous cooling at a constant shearing rate, the apparent viscosity of refined A356 slurry in the same solid fraction decreased with the content of Ti. It is shown from quantitative image analysis that the primary α-Al grain in the refined alloy evolves from dendrites to rosettes or sphericitys, and then tends to be rounder and finer in higher Ti content. The mechanism of the influence of morphology on rheological behavior was also discussed in this paper.

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