Trans. Nonferrous Met. Soc. China 26(2016) 1820−1825 Preparation of semi-solid ZL101 aluminum alloy slurry by serpentine channel Shu-jian CHENG, Yu-hong ZHAO, Hua HOU, Yu-chun JIN, Xiao-xiao GUO School of Materials Science and Engineering, North University of China, Taiyuan 030051, China Received 19 September 2015; accepted 9 December 2015 Abstract: Semi-solid slurry of ZL101 aluminum alloy was prepared using serpentine channel. The influences of the pouring temperature, the number of curves and the serpentine channel temperature on the microstructure of semi-solid ZL101 aluminum alloy were investigated. The results show that, satisfied semi-solid slurry of ZL101 aluminum alloy was prepared with pouring at 630−680 °C. The morphology of primary α(Al) grains transforms from rosette to spheroid with the decrease of pouring temperature. At the same pouring temperature, increasing the number of curves can improve the morphology of primary α(Al) grains and decrease the grain size. Qualified slurry can be attained with lowering the pouring temperature when the serpentine channel temperature is higher. The alloy melt has the effect of “self-stirring” in the serpentine channel, which can make the primary nuclei gradually evolve into spherical and near-spherical grains. Key words: ZL101 aluminum alloy; semi-solid; slurry; serpentine channel 1 Introduction As a kind of new near net shape metal processing technology, semi-solid processing (SSP) has the brightest future in the 21st century. A key step of semi-solid processing technology is an economical production of semi-solid metal slurry with fine grain microstructure [1−4]. In order to meet this demand, strong convection or shearing is often applied during the solidification, such as mechanical stirring [5,6], electromagnetic stirring [7,8]; however, the former pollutes alloy readily and the latter has low electromagnetic stirring efficiency. Recently, a controlled nucleation method has been reported, which is simple, practical and less expensive because of no application of stirring. These preparation methods include new rheocasting [9,10], vertical pipe [11,12], vibrating wavelike sloping plate process [13−15], inverted cone pouring channel [16,17] and cooling slope process [18−20]. These techniques have similarities, such as pouring the alloy melt through a plate or tube without stirring. Therefore, they reduce the energy consumption and save the cost of production greatly. On the basis of controlled nucleation method, serpentine channel process (SCP) was presented. The serpentine channel was made of stainless steel and consisted of two symmetrical blocks locked together by sleeve. During the period of preparing semi-solid slurry, the direction of alloy melt changed several times in the field of gravity, which made alloy melt have the function of “self-stirring” [21−25]. With the effect of stirring in serpentine channel, primary nuclei gradually evolved into spherical and near-spherical grains. In this work, an innovative processing technique of semi-solid metal slurry, namely serpentine channel process, was introduced, and effects of pouring process parameters on the microstructure of semi-solid ZL101 aluminum alloy slurry were investigated. 2 Experimental 2.1 Materials and apparatus In the experiment, a kind of commercial aluminum alloy named ZL101 was used. Its chemical composition is 6.6% Si, 0.28% Mg, <0.16% Fe, <0.10% Mn, <0.10% Zn and balance Al (mass fraction). Its liquidus and solidus temperatures are 615 and 556 °C, respectively, which were tested by differential scanning calorimetric (DSC) method. Foundation item: Projects (51204147, 51274175) supported by the National Natural Science Foundation of China; Project (2014DFA50320) supported by the Ministry of Science and Technology of China; Projects (2013081017, 2012081013) supported by the International Science and Technology Cooperation Project of Shanxi Province, China Corresponding author: Yu-hong ZHAO; Tel: +86-15035172958; E-mail: zyh388@sina.com DOI: 10.1016/S1003-6326(16)64293-0