Ideal Elastic, Anelastic, and Viscoelastic Flow in a Metallic Glass.
Abstract
The elastic, viscoelastic, and anelastic components of the homogeneous strain response of the metallic glass Pd82 Si18 to an applied stress have been examined. The elastic response is fully reversible, instantaneous, and linear. The measured elastic modulus and temperature dependence are E = 84 + or - 8 GPa and d(ln E) /dt = (-3.2 + or - 0.6) x 104/C. This viscoelastic flow is nonrecoverable, and, if the configuration remains constant, is characterized by a constant strain rate. This strain rate varies linearly with the stress in the low stress regime (tau <300 MPa), becoming nonlinear for higher stresses. For isoconfigurational flow, the strain rate has an Arrhenius-type temperatures dependence with an activation energy of -200 + or - 15 kJ/mole, independent of stress and thermal history. The magnitude of the strain rate is strongly dependent on the degree of structural relaxation and therefore on thermal history. During isothermal annealing, the viscoelastic strain rate varies inversely with time. The anelastic response is a transient that at 500 K contributes to the flow for approximately 50 hours after a stress increase and is fully recovered upon stress reduction. A spectrum of exponential decays is required to model this flow component. The anelastic strain varies linearly with the magnitude of the stress change over the entire stress range tested.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1982
- Accession Number
- ADA123893
Entities
People
- A. I. Taub
- F. Spaepen
Organizations
- Harvard University