Room-temperature vacancy emission from the jog on edge dislocation in FCC nickel under glide force

TL;DR

This study reveals that vacancy emission from jogs on edge dislocations in FCC nickel occurs at room temperature under stress, challenging the conventional view that such jogs only glide conservatively without vacancy emission.

Contribution

The paper uncovers unexpected vacancy emission from edge dislocation jogs during glide at room temperature, highlighting complex defect-dislocation interactions in plasticity.

Findings

Jogs on edge dislocations can climb and emit vacancies at 300K.

Vacancy emission occurs intermittently under higher stresses.

Edge dislocation jogs exhibit non-conservative motion at room temperature.

Abstract

Jogs, atomic-scale steps on dislocations, play an important role in crystal plasticity, yet they are often ignored in discrete dislocation dynamics (DDD) simulations due to their small sizes. While jogs on screw dislocations are known to move non-conservatively (i.e. climb) accompanied by vacancy emission, jogs on edge dislocations are commonly expected to move conservatively (i.e. glide) with the dislocation under ambient conditions. Here we report unexpected findings from molecular dynamics simulations of an edge dislocation containing a pair of unit jogs in face-centered cubic nickel at 300K. While the jogs glide conservatively with the edge dislocation at low stresses, we observe that one of the jogs climbs and emits vacancies intermittently at higher stresses. This observation is unexpected at such a low temperature, as climb is typically associated with temperatures closer to the creep temperature (roughly half of the melting temperature). Our results highlight the significance of the complex interplay between point defects (i.e., vacancies) and dislocations in room-temperature plasticity, suggesting that these interactions may be more significant than previously thought.