Effect of intensive shearing on morphology of primary silicon and properties of hypereutectic Al–Si alloy

Abstract

Al–17Si–0·01Sr alloy melt was intensively sheared in the liquid state using the melt conditioning by advanced shear technology (MCAST) process before high pressure die casting (HPDC). The resultant microstructure and mechanical properties were examined and compared with those of the same alloy produced by the conventional HPDC process. It was found that intensive melt shearing can result in fine and equiaxed primary silicon particles uniformly distributed in the aluminium matrix, giving rise to much improved ductility and wear resistance.

Fabrication of Metal Matrix Composites under Intensive Shearing

“…High turbulent flow in the axial direction was necessary to obtain fairly uniform particle distribution. The stirring condition, melt temperature, and the type, amount and nature of the particles are some of the main factors that are being investigated further [13,14]. The process parameters for distributive mixing are to be optimised further by conducting experiments with various types of impellers designed to achieve homogeneous distributive mixing in chemical, pharmaceutical, mining and food processing technologies [15].…”

Fabrication of Metal Matrix Composites under Intensive Shearing

“…High turbulent flow in the axial direction was necessary to obtain fairly uniform particle distribution. The stirring condition, melt temperature, and the type, amount and nature of the particles are some of the main factors that are being investigated further [13,14]. The process parameters for distributive mixing are to be optimised further by conducting experiments with various types of impellers designed to achieve homogeneous distributive mixing in chemical, pharmaceutical, mining and food processing technologies [15].…”

“…Fine and homogeneous microstructure, unlike conventional MMC, rheo-processed MMC, is expected to improve simultaneously the tensile strength and ductility [24]. Simultaneous improvement in the mechanical strength and ductility has been observed in these rheoprocessed Al/SiC composites and the detailed results will be published elsewhere [13,14]. High resolution microscope shows presence of clean interface between Al/SiC matrix for most of the SiC particulates that are embedded in Alalloy matrix, suggesting that the rheo-process (mixing liquid with particulates under intensive shearing) results in absence of chemical reaction between the particle and liquid metal due primarily to the short time involved in mixing process.…”

The dispersive orientated-precipitation of AlP on alumina film and its effect on the primary Si gathering behavior in the Al–Si alloy surface layer

“…[14][15][16][17] In recent years, a lot of evidence has been reported that supports that γ-Al 2 O 3 is a potential substrate for the nucleation of the Si phase, [18][19][20][21][22] and some researchers have studied the influence of in situ γ-Al 2 O 3 on the microstructure of Al-Si alloys. [23][24][25][26][27] In the field of forming silicon-on-insulator (SOI) materials, γ-Al 2 O 3 film is also an important epitaxial substrate for Si. 28,29 We have noticed that AlP particles tend to be attached by γ-Al 2 O 3 slag, which leads to the loss of part of the AlP phases and a lower P absorb rate.…”