Effect of Chilling on Soundness, Micro Hardness and Ultimate Tensile Strength of Nickel Alloy-Fused Silica Metal Matrix Composite

An investigation has been carried out to fabricate and evaluate the strength and soundness of chilled composites consisting of nickel matrix and fused silica particles (size 40?150 μm) in the matrix. The dispersoid added ranged from 3 to 12 wt. % in steps of 3%. The resulting composites cast in moulds containing metallic and non metallic chill blocks (MS, SiC& Cu) were tested for their microstructure, hardness and tensile strength properties. The main objective of the present research is to obtain fine grain Ni/SiO2 chilled sound composite having very good properties. Results of the investigation reveal the following: (1) Strength of the composite developed is highly dependent on the location of the casting from where the test specimens are taken and also on the dispersoid content of the composite. (2) Chill thickness and chill material, however, does significantly affect the strength and soundness of the composite. (3) Soundness of the composite developed is highly dependent on the chilling rate as well as the dispersoid content