In Situ Studies on Twin-Thickness-Dependent Distribution of Defect Clusters in Heavy Ion-Irradiated Nanotwinned Ag
- PDF / 2,278,837 Bytes
- 8 Pages / 593.972 x 792 pts Page_size
- 94 Downloads / 233 Views
INTRODUCTION
HEAVY ion irradiations can introduce a significant amount of defect clusters in metallic materials including dislocation loops, vacancy clusters, precipitates, and voids.[1–3] Consequently, the mechanical properties of irradiated metallic materials can be severely undermined in terms of irradiation hardening, embrittlement, void swelling, etc.[4–8] Numerous types of high-energy boundaries, such as grain boundaries (GBs), phase boundaries, and free surfaces, have proven to be effective defect sinks that can alleviate irradiation damage in materials.[9–21] For instance, molecular dynamics (MD) simulations show that GBs can act as efficient defect sinks by absorbing irradiation-induced interstitials or serve as sources to emit interstitials to annihilate vacancies.[22] Grain boundary-affected zones [GBAZs, or grain boundary-denuded zones (GBDZs)] have been reported in several previous studies, where the concentration of defect clusters, such as dislocation loops or He bubbles, is drastically reduced near GBs.[23–25] In metallic multilayers, certain types of layer interfaces can act as efficient defect sinks, and size-dependent enhancement of radiation tolerance was observed in various multilayer systems.[21,26–29] In addition, free surface may have infinite sink capacity, and nanoporous (np) materials with a large surface-to-volume ratio may have superior irradiation resistance.[18,20,30]
JIN LI is with the Department of Materials Science and Engineering, Texas A&M University, College Station, TX 77843-3123. Y. CHEN is with MPA-CINT, Los Alamos National Laboratory, Los Alamos, NM 87545. H. WANG is with the Department of Electrical and Computer Engineering, Purdue University, West Lafayette, IN 47907, and also with the School of Materials Engineering, Purdue University, West Lafayette, IN 47907. X. ZHANG is with the School of Materials Engineering, Purdue University. Contact e-mail: [email protected]. Manuscript submitted August 27, 2016. Article published online January 4, 2017 1466—VOLUME 48A, MARCH 2017
Compared to the aforementioned high-energy defect sinks, twin boundaries (TBs) are low-energy boundaries and are generally anticipated to be less efficient defect sinks. Han et al. showed that the width of void denuded zone in non-R3 GBs is much greater compared to R3 TBs, indicating low sink efficiency of TBs.[24] A recent study on He ion implantation of nanotwinned (nt) Cu at room temperature suggested that TBs are poor sinks because point defects at R3 TBs have nearly identical properties to those in crystal lattices of the face-centered cubic (fcc) Cu.[31] However, Niewczas and Hoagland reported, through MD simulations, that the interaction between R3 {111} coherent twin boundaries (CTBs) and stacking fault tetrahedra (SFTs) leads to the destabilization of SFTs.[32] Yu et al. validated the MD simulation experimentally using in situ Kr ion irradiation study of nt Ag and showed that the density of SFTs in nt Ag is much lower than that in its bulk counterpart.[14] They also observed the frequent migration of inc
Data Loading...
