Article ID: MT-M2025098
Sintered Ag nanoparticles display brittle fatigue crack propagation behavior at 298 K because of their submicron-size crystals. On the other hand, at elevated test temperatures above 413 K, ductile fatigue crack propagation characteristics similar to those of soft metals such as solder appear owing to viscous creep behavior at the grain boundaries, and no temperature dependence of the fatigue crack propagation properties was observed. The fatigue crack initiation lives observed experimentally and the fatigue lives derived by a pseudo-fracture mechanics approach using numerical fatigue tests with the fatigue crack propagation law mostly coincided with each other. However, the fatigue crack initiation life was calculated on the excessively safe side because of the long incubation period for crack initiation due to the influence of continued sintering during the tests performed near the sintering temperature. The application of the pseudo-fracture mechanics approach made it possible to derive the fatigue crack initiation law for smooth specimens of sintered Ag nanoparticles with satisfactory accuracy if the test temperature is lower than the sintering temperature.
