Abstract
In the present work stir casting route is used to fabricate the ZA27 Metal matrix composites containing 3 wt%, 6 wt%, 9 wt%, and 12 wt%. Zircon sand particulates of size 100 mesh. Microstructure studies using Optical Microscopy, SEM-EDAX are carried out to ascertain the distribution and morphology of particulates in the composites. Effect of zircon sand as reinforcement on bulk density, porosity, of the fabricated composites is studied. SEM studies are carried out to understand the behavior of as-cast ZA27 alloy reinforced with zircon sand. The dislocation density of the fabricated composite affects the strength of the composites and depends on the strain due to thermal mismatch and is found to increase with increase in weight% of zircon sand. However, it does not consider casting defects of voids/clustering observed in micrographs of the fabricated composite. Porosity in composites does not have influence on Coefficient of thermal expansion (CTE) of the ZA27 composites studied using thermoelastic models like Kerner and turner model and rule of mixtures of composite.
Highlights
The thermal coefficients of zircon sand is low compared to other oxides of ceramics improving the interface strength, the density of zircon sand (ρ = 4.56 g/cc) is in close proximity with the density of ZA-27 (ρ = 4.5 g/cc) alloy which reduces the problems of gravity segregation due to large density difference between matrix phase and dispersed phase (Figure 2 and Table 2)
Theoretical density is calculated using the rule of mixture
Minerals and Materials Characterization and Engineering difference (ΔT) due to cooling of composites, plastic deformation of ZA27 alloy matrix is likely to occur in order to accommodate elastic residual stress that forms in matrix, Coefficient of thermal expansion (CTE) mismatch will be large at interface due to work hardening setting up dislocations formed during cooling of composite whose movements are arrested at particle and matrix interface and exhibits large hardness which decreases with increasing distance from interface
Summary
Over the past few decades research on zinc-based alloys are being carried out and found to exhibit excellent tribo-mechanical properties apart from low melting point, good cast ability and machinability. There is not much work carried out on characterization of zircon sand reinforced with ZA27 alloy especially beyond 5% weight fraction micro-mechanical behavior of such composites [6]. The thermal coefficients of zircon sand is low compared to other oxides of ceramics improving the interface strength, the density of zircon sand (ρ = 4.56 g/cc) is in close proximity with the density of ZA-27 (ρ = 4.5 g/cc) alloy which reduces the problems of gravity segregation due to large density difference between matrix phase and dispersed phase (Figure 2 and Table 2). The composite was poured at 500 ̊C into the preheated cast iron die for better solidification [6]
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More From: Journal of Minerals and Materials Characterization and Engineering
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