Action of Chills on Microstructure, Mechanical Properties of Chilled ASTM A 494M Grade Nickel Alloy Reinforced with Fused SiO2 Metal Matrix Composite

In the field of engineering, metallurgists are looking for ways to improve the mechanical properties of the materials. By doing so it is possible to improve the quality of the materials which in turn gain the International market share. Therefore in the present research work, an investigation has been carried out to fabricate and evaluate the microstructure, strength, micro hardness of chilled composites consisting of nickel matrix and fused SiO2 particles as the reinforcement (size 40-150 μm) in the matrix. The reinforcement being added ranges from 3 to 9 wt. % in steps of 3%. The resulting composites cast in moulds containing metallic chill blocks (MS & SiC) were tested for their microstructure and mechanical properties. The main objective of the present research is to obtain fine grain Ni/SiO2 chilled sound composite having very good mechanical properties. A detail of melting and composite preparation is described elsewhere by number of researchers. After melting the matrix material in an induction furnace at around 1600 ̊C in an inert atmosphere, coated fused SiO2 particles preheated to 500 ̊C were introduced evenly into the molten metal alloy by means of special feeding attachments. The moulds for the plate type of castings 150*20*20 mm (American Foundrymen Society standard) were prepared using silica sand with 5% bentonite as binder and 5% moisture and finally they were dried in an air furnace at a temperature of 1580 ̊C, which was cooled from one end by a chill block set in the mould. After solidification the specimens of chill end were tested for various mechanical and microstructural studies.