Fabrication and Characterization of a Hybrid Functionally Graded Metal-matrix Composite Using the Technique of Squeeze Infiltration

Abstract

In this research paper, the results of a recent study that focussed on preparing hybrid and graded cylindrical preforms by stacking alumina-silicate fibre, SiC particles and the pore forming agent in different layers along with aluminium powder as the binding agent and the resultant mixture sintered at a high temperature is presented and discussed. The stacked preforms were compacted and sintered above the melting temperature of aluminium. Decomposition of the fugitive pore former was done using the leaching technique. Direct squeeze infiltration of aluminium alloy 319 on a graded hybrid preform was successfully carried out using controlled process parameters spanning initial preform temperature, liquid metal superheat, squeeze pressure and its rate of application, and die temperature. The liquid metal did fully infiltrate through the ceramic preform to form a functionally graded composite. The resultant composites were characterized using the techniques of scanning electron microscopy, optical microscopy, x-ray diffraction and measurement of density. The extrinsic influence of infiltration pressure, preform temperature and mold temperature on microstructural development and hardness of the engineered composites is briefly highlighted.