Ambient and non-ambient temperature depth-sensing indentation of Mg-Sm2O3 nanocomposites

Abstract

Magnesium matrix nanocomposites (Mg-Sm2O3 nanocomposites in the present study), containing nanosize reinforcements within the magnesium or magnesium alloy matrix, are a group of energy-saving novel material with enhanced strength-to-weight ratio. However, in order to scale up the applications of the magnesium nanocomposites toward industrial dimensions, detailed response of the materials at ambient and elevated temperatures must be established. Having said this, the primary objective of this paper is to obtain an in-depth understanding of small-scale property–microstructure-composition correlation at ambient (298 K) temperature up to 473 K using a depth sensing nanoindentation testing approach as well as advanced microstructural characterization. Mg-Sm2O3 nanocomposites with 0.5, 1.0, and 1.5 vol% Sm2O3 were compared against pure Mg. The properties measured are reduced modulus, elastic modulus, hardness, indentation creep rate, indentation creep exponent, thermal activation volume, as well as indentation size effect as a function of temperature. Pure Mg and Mg-1.0 Sm2O3 nanocomposite provided the least and the greatest creep resistance, respectively. This is attributed to the presence of thermally stable Sm2O3 nanoparticles which can effectively produce dislocation pile-ups and dislocation tangling.