Fabrication of Metal Matrix Composites under Intensive Shearing

Abstract

Abstract. Current processing methods for metal matrix composites (MMC) often produces agglomerated reinforced particles in the ductile matrix and also form unwanted brittle secondary phases due to chemical reaction between matrix and the reinforcement. As a result they exhibit extremely low ductility. In addition to the low ductility, the current processing methods are not economical for producing engineering components. In this paper we demonstrate that these problems can be solved to a certain extent by a novel rheo-process. The key step in this process is application of sufficient shear stress on particulate clusters embedded in liquid metal to overcome the average cohesive force of the clusters. Very high shear stress can be achieved by using the specially designed twin-screw machine, developed at Brunel University, in which the liquid undergoes high shear stress and high intensity of turbulence. Experiments with Al alloys and SiC reinforcement reveal that, under high shear stress and turbulence conditions Al liquid penetrates into the clusters and disperse the individual particle within the cluster, thus leading to a uniform microstructure.

Processing Route Optimization and Characterization of Al6063–SiCp Metal-Matrix Composite Sheets

“…In order to explain why finer sizes such as 8 µm F800 particles show a higher tendency to develop agglomeration features, the shear stress applied to the particle clusters that should overcome the cohesive force between the SiCp should be estimated (Babu et al, 2008) [18]. The shear rate 'γ' can be expressed as a ratio between stirrer frequency 'n' and geometric parameter 'k' according to the following equation:…”

Significance of fabrication parameters over the mechanical and metallurgical properties of AMMC joint formed by microwave hybrid heating

“…These MMCs offer far superior characteristics, e.g. higher specific strength, better structural proficiency, consistency, wear resistance and control over its physical properties; mainly coefficient of thermal expansion and density which in turn provides improved mechanical performance when compared with the monolithic materials and alloys (Segurado et al , 2003; Deng and Chawla, 2006; Su et al , 2012; Corbin and Wilkinson, 1994; Basavarajappa et al , 2007; Ahmad et al , 2013; Babu et al , 2008).…”

Characterization of aluminium metal matrix composite fabricated by gas injection bottom pouring vacuum multi-stir casting process

“…These MMCs offer far superior characteristics, e.g. higher specific strength, better structural efficiency, reliability, wear resistance and control over its physical properties such as coefficient of thermal expansion and density which in turn provides better technical performance when compared with the monolithic materials [2][3][4][5][6][7][8].…”