Seminars and Events

Can slow-diffusing solute atoms reduce vacancy diffusion in Ni-based superalloys?

Date/Time: 16.09.2014. 11:50 a.m.
Place: Ruhr-Universität Bochum, Bochum, Germany

Kamal Nayan Goswami, University of Birmingham, Birmingham, United Kingdom

The high-temperature mechanical properties of Ni-based superalloys can be heavily influenced by adjusting the chemical composition. The widely-accepted argument is that under certain temperature and loading conditions, plasticity occurs only in the γ matrix, and dislocations have to rely on thermally-activated climb mechanisms to overcome the barriers to glide posed by the γ' precipitates. The presence of dilute amounts of slow-diffusing solute atoms, such as Re, in the γ matrix is thought to reduce plasticity by retarding the climb of dislocations at the γ/γ' interface. One hypothesis is that the presence of these solutes must hinder the flow of vacancies, which are essential to the climb process. In this work, density functional theory calculations were used to inform an analytical model to describe the effect of solute atoms on the diffusion of vacancies. Results suggest that slow-diffusing solute atoms are not effective at reducing the diffusion of vacancies in these systems.

« back