The influence of structural relaxation on the density and Young’s modulus of metallic glasses

The Young’s modulus E of metallic glasses increases by ∼7% while the density ρ increases by only ∼0.5% upon annealing near the glass transition temperature. ρ and E of an ’’ideal’’ glass are calculated to approach the crystalline values within 0.5 and 10%, respectively. The large decrease in E of ∼30% observed upon vitrification of many glass-forming alloys may be attributed mainly to the frozen-in excess volume. The rates of increase in E associated with decrease in volume V, −d lnE/d lnV, during structural relaxation, crystallization, and thermal expansion are large and ∼15, 17, and 10, respectively. Structural reconstruction and consequent electron redistribution near the Fermi surface are suggested to be responsible for the large −d lnE/d lnV observed.