In-situ atomic-scale observation of irradiation-induced void formation

• Published in: Nature communications Vol. 4; no. 1; p. 2288
• Main Authors: Xu, Weizong, Zhang, Yongfeng, Cheng, Guangming, Jian, Weiwei, Millett, Paul C., Koch, Carl C., Mathaudhu, Suveen N., Zhu, Yuntian
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 05.08.2013; Nature Publishing Group
• Subjects: 639/301/1034; 639/766/36; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms3288

The formation of voids in an irradiated material significantly degrades its physical and mechanical properties. Void nucleation and growth involve discrete atomic-scale processes that, unfortunately, are not yet well understood due to the lack of direct experimental examination. Here we report an in-situ atomic-scale observation of the nucleation and growth of voids in hexagonal close-packed magnesium under electron irradiation. The voids are found to first grow into a plate-like shape, followed by a gradual transition to a nearly equiaxial geometry. Using atomistic simulations, we show that the initial growth in length is controlled by slow nucleation kinetics of vacancy layers on basal facets and anisotropic vacancy diffusivity. The subsequent thickness growth is driven by thermodynamics to reduce surface energy. These experiments represent unprecedented resolution and characterization of void nucleation and growth under irradiation, and might help with understanding the irradiation damage of other hexagonal close-packed materials. The irradiation of crystalline materials is known to create various types of lattice defects, which can degrade mechanical performance. Here, Xu et al. observe the in-situ nucleation and growth of atomic-scale voids in magnesium during electron irradiation.