Deformation behaviour of Mg/Y2O3 nanocomposite at elevated temperatures

In this study, we focused on the tensile deformation behaviour of Mg and Mg/Y2O3 nanocomposite that includes temperature dependent strength, ductility, strain rate sensitivity and activation volume. Bulk nanocomposite with monolithic Mg as the matrix, reinforced by 2 vol.% nano-yttria (Y2O3) particulate was prepared by powder metallurgy technique incorporating energy efficient microwave assisted rapid sintering process followed by hot extrusion. Results revealed that the presence of thermally stable nano-Y2O3 particulates as reinforcement leads to a significant improvement in 0.2% yield strength and tensile strength at all test temperatures (25–250 °C) when compared to pure Mg. No apparent necking was detected in the composite samples following tensile testing at any of the test temperatures. These results suggest that an increase in test temperature up to 250 °C does not affect the homogeneous deformation process exhibited by the composite samples. Strain rate sensitivity and the apparent activation volume were measured by the repeated stress relaxation test. High strain rate sensitivity and low activation volume at room temperature as compared to pure Mg suggest that different rate controlling deformation mechanisms exist in the composite samples. Low temperature sensitivity was observed in the composite.