Radiation damage in materials can affect:
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changes in shape and volume by 10%+
increases in hardness by factors of 5+
severe reduction in ductility
severe increase in embrittlement,
susceptibility to environmentally induced cracking
Frenkel pairas (vacancy-interstitial pairs in a crystalline lattice) and other consequences of irradiation
damage determine the physical effects, and with the application of stress, the mechanical effects of
irradiation by the occurring of interstitial, phenomena, such as swelling, growth, phase
transition, segregation, etc., will be effected.
Ions/Electrons/Protons
In addition to the atomic displacement, an energetic charged particle moving in a lattice also gives energy
to electrons in the system, via the electronic stopping power. This energy transfer can also for highenergy particles produce damage in non-metallic materials, as so called ion tracks.[1][2]
Damge due to Ions extends the problem to:
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use of accelerators for the transmutation of nuclear waste
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the creation of new materials by ion implantation, ion beam mixing, plasma assisted ion
implantation and ion beam assisted deposition.
Modeling
TRIM operates on a Monte Carlo basis with the probability of an atomic displacement (and creation of a
vacancy) given by the ion energy over the threshold displacement energy at any time on the track. The
energy is dissipated according to the relevant stopping powers as it proceeds along its track.
TRIM produces a distribution of tracks that it then averages to give vacancies created per ion etc. This
can be converted to a value for dpa (displacements per atom) in the material. The accumulation of
damage (amorphous fraction) follows simple laws.
LAMMPS is a classical MD simulator. LAMMPS has potentials for soft materials (biomolecules, polymers)
and solid-state materials (metals, semiconductors) and coarse-grained or mesoscopic systems. It can be
used to model atoms or, more generically, as a parallel particle simulator at the atomic, meso, or
continuum scale. Uses material “Potentials” to predict probability of interaction.
TRIM requires much less computational power than LAMMPS as it uses simplified physics and collision
approximations.
SPPARKS is a KMC code
Radiation Damage to Materials
Potential Applications
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Nuclear Waste applications (and in the waste itself)
From Nuclear Reactor Operations (Effect of temperature on damage for various fluxes)
In Accelerator Applications (allows for more specific, uniform fluence to be specified)
Effect on Material Properties
Mechanical Properties
Incident radiation causes atomic displacements within a materials lattice structure. The change
in a materials microstructure can cause changes in the following macroscopic properties:
Hardness, Strength, Toughness, Ductility, Creep Rate, Thermal Conductivity, Electrical
Conductivity, Swelling
Relationships to explore:
Radiation Fluence & Energy Vs. Atomic Displacements (defect formation)
Displacements Vs. macroscopic properties (above)
Radiation Fluence & Energy Vs. Ionization
Ionization vs Energy Deposition
Energy Deposition Vs. Molecular Bonding
Molecular Bonding Vs. Electrical/chemical properties
Energy Deposition Vs. Thermal Heating
Thermal Heating vs. Macroscopic properties (above)
Resources
Fundamentals of Radiation Materials Science: Metals and Alloys
By Gary S. Was