Rheo-Processing of Near-Eutectic ADC12 Alloy

Abstract

It is demonstrated experimentally that by using the mechanical rotational barrel processing system combined with high pressure die casting machine, the near-eutectic ADC12 alloy is possible to be rheo-processed. Microstructural characteristics of the semisolid slurry were investigated in different processing parameters. Microstructural evolution and solidification behavior of the semisolid slurry were discussed. The result shows that, the dendritic primary α-Al was sheared off by the vertical stress supplied by the rotational barrel. With a rotation speed of 30r/min and 40r/min, the semisolid slurry can achieve relatively high solid fraction. When the pouring temperature decreased from 620°C to 580°C, the morphology of the primary α-Al changed from spheroidal to rosette-like. Besides, the average grain size and solid fraction increased with the decreasing of pouring temperature. The solidification of the alloy melt during the rheo-diecasting process is composed of two distinct stages: the primary solidification and the secondary solidification. By using the rheo-diecasting process, the components with fine, spherical and uniformly distributed primary α-Al particles were successfully obtained. As the pouring temperature descended from 605°C to 585°C, the primary α-Al of the rheo-diecasting components had rounder morphology, larger average grain size and higher solid fraction.

Optimization of processing parameters of cooling slope process for semi-solid casting of ADC 12 Al alloy

“…ADC 12 aluminium alloy has excellent material properties such as high castability, high fluidity and low shrinkage rate [15,16]. Few investigators have attempted to modify the cast structure of ADC 12 Al alloy using Gas Induced semi solid technique (GISS), Strain-Induced metal activation (SIMA) and Mechanical-Rotatinal-Barrel (MRB) [17][18][19][20][21]. The primary objective of this work is to incorporate rheocasting process using cooling slope technique for ADC 12 Al alloy and thereby optimization of processing parameters of cooling slope process using the response surface methodology.…”

An Overview on the Process Development and the Formation of Non-Dendritic Microstructure in Semi-Solid Processing of Metallic Materials

“…Although the semi-solid principle has been reasonably understood for the alloys solidified in a temperature range [169,170], it has found the eutectic alloys and pure metals that solidify with a solid-liquid fraction ratio during thermal arrest at a fixed temperature, which can also be processed to form semi-solid slurry [169,[217][218][219][220][221], as shown in Figure 22. This confirms that semi-solid slurry can be formed by controlling the temperature, and/or by controlling the time of solidification process.…”

Refinement of primary Si in Al–20%Si alloy by MRB through phosphorus additions

“…Chirita et al (2009) found that under ultrasonic vibration treatment, the hydrogen pores and shrinkage porosities in the alloy were reduced, the primary Si phase was refined and the microstructures became more homogenous. The MRB process used in the present work has been successfully used to prepare high-quality semi-solid slurry of ADC12 alloy by Hu et al (2012). The average particle size of primary Si phase obtained through the mentioned semi-solid method was usually higher than 50 m which still cannot perfectly meet the requirements in industrial applications.…”