Structure and mechanical properties of internally hydrided Mg-III_a transition metal alloys

Abstract

Magnesium alloys containing III_a transition metals, such as Sc, Y and Ho, respectively, were hydrogenated at 773 K and examined for microstructure, X-ray diffraction pattern, micro-Vickers hardness, and tensile properties at room and high temperatures. Results obtained are as follows:

• 1. The alloys, respectively, have been internally hydrided and have precipitated hydrides of the III_a transition metals as small flake-like particles in the matrix and at grain boundaries, as well as twin boundaries.

• 2. The dispersed hydride particles do not necessarily contribute to further hardening of the alloys at room temperature and up to near 673 K.

• 3. However, the dispersed particles are very stable and seem to improve mechanical properties of the alloys above 673 K.

• 4. Presumed relationships of crystallographic coincidence between the matrix and hydrides have been obtained.