Time resolved evolution of the 3D nanoporous structure of sintered Ag by X-Ray nanotomography: role of the interface with a copper substrate

TL;DR

This study uses in-situ X-ray nanotomography to analyze how the nanoporous structure of sintered silver evolves at high temperatures, revealing the influence of a copper interface on pore growth mechanisms and kinetics.

Contribution

It provides new insights into the role of copper interfaces in accelerating pore evolution and the transition from Ostwald ripening in sintered silver at elevated temperatures.

Findings

Large pores dominate evolution, smaller pores are absorbed without significant change.

Copper interface accelerates pore growth kinetics compared to pure silver.

A temperature-dependent transition from Ostwald ripening to other mechanisms occurs.

Abstract

The evolution of the nanoporous structure of cylindrical sintered silver samples during high temperature aging, ranging from 200 {\textdegree}C to 350 {\textdegree}C for 350 min, is studied through in-situ Computed X-Ray Tomography. Investigations were performed for two types of specimens: pure sintered silver and 2 specimens containing a silver-copper interface. It is shown that the overall pore evolution is driven by the evolution of very few large ones. The smaller pores, although being more numerous, do not really evolve before being absorbed by the few bigger ones. In pure silver, pore evolution is driven by diffusion (Ostwald ripening) but the presence of an interface promotes faster growth kinetics until the aging time reaches a threshold value, after which a deviation from Ostwald ripening occurs. The transition is a function of the aging temperature. This behavior is associated with the competition between elastic relaxation and surface energy minimization.