Development and Property Evaluation of Copper-Chilled Aluminum Alloy Reinforced with Nano-ZrO2 Metal Matrix Composites (NMMCS)

摘要

The present investigation aims at developing aluminum alloy-nano particles composites (NMMCs) in moulds containing copper chill by reinforcingnano-Zro2 particulates in aluminum alloy (LM 13) by vortex method. The size of particulates dispersed varies from 90 to 100nm and the amount of addition varies from 3 to 12wt% in steps of 3%. The resultant composites cast using copper chills were tested for their strength, hardness and fracture toughness. Results of the investigation revealthat presence of nano-ZrO2 particles as dispersoid (up to 9Wt. %) and VHC of the chill used has improved significantly the strength, hardness and fracture toughness with slight reduction in ductility. The strength of the composite developed is highly dependent near to chill end and also on the reinforcement content present in the composite. Increase in the chilling rate and increase in the reinforcement content of the material both results in an increase in UTS and fracture toughness of the developed composite. Fractography of the specimens showed that the fracture behavior of matrix alloy has changed from ductile intergranular mode to cleavage mode of fracture.Microstructural analysis of the developed nano-composite reveals the uniform distribution of the reinforcement in the matrix alloy with significant grain refinement.