Extended defect transformations

Amorphous pocket to I311

DADOS implements a model which assumes that when the number of interstitials in an amorphous pocket is higher than a threshold, then the structure is automatically transformed into a I311.

The threshold in number of interstitials is given by:

Where:

• size0_Clusterto311 is the prefactor.
• EClusterto311 is the activation energy with changed sign.
• See symbol list.

However, there is a minimum size to create a I311, specified by parameter MIN311SIZE. Therefore, if the threshold is smaller than it, DADOS will discard it and use MIN311SIZE.

Amorphous pocket to void

DADOS implements a model which assumes that when the number of vacancies in an amorphous pocket is higher than a threshold, then the structure is automatically transformed into a void.

The threshold in number of vacancies is given by:

Where:

• size0_ClustertoVoids is the prefactor.
• EClustertoVoids is the activation energy with changed sign.
• See symbol list.

However, there is a minimum size to create a Void, specified by parameter MINVoidSIZE. Therefore, if the threshold is smaller than it, DADOS will discard it and use MINVoidSIZE.

I311 to dislocation loop

Two models are implemented in DADOS to simulate the creation of dislocation loops from I311 (Castrillo et al. 2005). It is highly recommended to have only one of them active.

Transition size model

To deactivate this model, please set size0_311toDLoop to negative.

This model assumes that when the number of particles is higher than a threshold, then the structure is automatically transformed into a dislocation loop.

The threshold in number of interstitials is given by:

Where:

• size0_311toDLoop is the prefactor.
• E311toDLoop is the activation energy.
• See symbol list.

Transition rate model

To activate this model, please set R0_311ToDL to zero.

This model says that the transformation rate follows an Arrhenius plot from a value, as shown in the figure:

The barrier energy to create dislocation loops is dependent on the number of interstitials as follows:

Where:

• Ebar0_311ToDL is a constant energy. It is the limit barrier energy for high structure sizes.
• Ebar1_311ToDL is a prefactor used to define the growth level in the rate.
• N is the number of interstitials in the structure.
• N₀ is a fixed value. It is the number of interstitials for which the formation energy for I311 and dislocation loops is the same.
• expo_311ToDL is an exponent used to define the growth level in the rate.

The transformation rate is then given by:

Where:

• R0_311toDLoop is the prefactor.
• Ebarr is the barrier energy calculated before.
• See symbol list.