Effect of Crystal Orientation on Dislocation Loop Evolution Under Electron Radiation in Pure Aluminum

Area of Science:

• Materials Science
• Nuclear Engineering
• Aerospace Engineering

Background:

• Spacecraft structural material aluminum faces high-energy electron irradiation in low Earth orbit.
• Irradiation induces significant damage, impacting spacecraft component integrity.
• Understanding defect characteristics is vital for enhancing material radiation resistance.

Purpose of the Study:

• To analyze irradiation defect characteristics in pure aluminum across different crystallographic orientations.
• To compare the interstitial atom density (IAD) in <111> and <110> dislocation loops.
• To determine the relationship between crystallographic orientation and threshold displacement energy (Ed).

Main Methods:

• In situ irradiation of pure aluminum using 200 kV transmission electron microscopy at room temperature.
• Comparative analysis of irradiation defects for four crystallographic orientations.
• Focus on size, density, and interstitial content of <111> and <110> dislocation loops.

Main Results:

• <111> dislocation loops consistently exhibit higher interstitial atom density (IAD) than <110> loops across all irradiation directions.
• Under [110] irradiation, <111> loops show ~55 times higher IAD than <110> loops, attributed to <110> loop migration.
• Total IAD order: [110] > [111] > [310] > [100].

Conclusions:

• Crystallographic orientation significantly influences irradiation defect formation and interstitial atom density in aluminum.
• <111> loops are more effective sinks for interstitials than <110> loops, especially under [110] irradiation.
• The inferred threshold displacement energy (Ed) follows: [110] < [111] < [310] < [100].