Radiation tolerance in a nanostructure: Is smaller better?

✍ Scribed by T.D. Shen

• Book ID: 103862740
• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 146 KB
• Volume: 266
• Category: Article
• ISSN: 0168-583X
• DOI: 10.1016/j.nimb.2008.01.039

✦ Synopsis

While previous experimental studies suggest that the presence of nanostructure is detrimental to the phase-transition resistance under an irradiation environment, we have recently found an opposite effect -nanostructure enhances phase-transition resistance. Here we analyze the change in free energy of an irradiated single-phase nanocrystalline material and explain the radiation tolerance (characterized by the resistance to phase-transition) in terms of two competing effects: (i) a smaller grain size tends to lower the free energy because the accumulation of point defects (mainly vacancies) in the grain interior is suppressed and (ii) a smaller grain size tends to increase the free energy because the area fraction of grain boundary is larger. For a two-phase nanocrystalline material, the heat of mixing between the two-phases often needs to be sufficiently positive so that the ion-beam mixing is avoided. Our analysis explains all previous experimental results where a nanostructure is found to either enhance or lower the phase-transition resistance.