Effect of third elements on the microhardness of Ni 3Al

Abstract

The room-temperature microhardness of Ni 3Al with and without third elements has been studied using the Vicker's indentation technique. In pure Ni 3Al phase alloys, the hardness value increased with decreasing Al concentration from stoichiometric composition. This increase is attributed to the defects present at off-stoichiometric compositions. The addition of third elements Hf, Zr, Ti and Si increased the hardness value of Ni 3Al suggesting the solid-solution strengthening effect. The presence of 0.20 at% boron in Hf- and Zr-containing alloys shows a softening effect at small concentrations of Hf and Zr.