Impression creep of Sn3.5Ag eutectic alloy

The creep behavior of Sn3.5Ag eutectic alloy was investigated by using impression technique in the temperature range of 333-453 K and under the punching stress range of 3.4-67.1 MPa. Using a power law between the steady-state impression velocity and the punching stress, it was found the activation energy increases with the punching stress from 44.7 kJ/mol at 6.7 MPa to 79.2 kJ/mol at 46.9 MPa and the stress exponent changes from 1.03 (3.4-13.4 MPa) to 5.9 (20.1-40.2 MPa). However, by using a hyperbolic sine function between the steady-state impression velocity and the punching stress, a single activation energy was found to be 5 1.0 kJ/mol, which is close to the activation energy for grain boundary diffusion in pure Sn. This suggests that a single mechanism of grain boundary fluid flow is likely the controlling mechanism for the time-dependent plastic flow of Sn3.5Ag eutectic alloy under the testing conditions. (c) 2005 Elsevier B.V. All rights reserved.