Effects of Helium Ion Irradiation on Properties of Crystalline and Amorphous Multiphase Ceramic Coatings
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JMEPEG DOI: 10.1007/s11665-017-2793-5
Effects of Helium Ion Irradiation on Properties of Crystalline and Amorphous Multiphase Ceramic Coatings Yong Chen, Liangbin Hu, Changjun Qiu, Bin He, and Zhongchang Wang (Submitted October 20, 2016; in revised form June 8, 2017) The Al2O3-TiO2 crystalline and amorphous multiphase ceramic coatings were prepared on a martensitic steel by laser in situ reaction technique and impose irradiation with 200 keV He ions at different doses. The helium ion irradiation goes 1.55 lm deep from the surface of coating, and the displacement per atom (dpa) for the Al2O3-TiO2 coating is 20.0. When the irradiation fluency is 5 3 1017 ions/cm2, defects are identified in crystalline areas and there form interfacial areas in the coating. These crystal defects tend to migrate and converge at the interfaces. Moreover, helium ion irradiation is found to exert no effect on surface chemical composition and phase constitution of the coatings, while surface mechanical properties for the coatings after irradiation differ from those before irradiation. Further nano-indentation experiments reveal that surface nano-hardness of the Al2O3-TiO2 multiphase coatings decreases as the helium ions irradiation flux increases. Such Al2O3-TiO2 crystalline and amorphous multiphase ceramic coatings exhibit the strongest resistance against helium ion irradiation which shall be applied as candidate structural materials for accelerator-driven sub-critical system to handle the nuclear waste under extreme conditions. Keywords
Al2O3-TiO2 multiphase ceramic coatings, helium ion, irradiation effects, laser in situ reaction
1. Introduction The properties of nuclear reactor materials may be altered significantly due to the irradiation damage. One of the key issues in irradiation is that point defects could be produced, shifting remarkably behaviors and configuration of the host materials after irradiation (Ref 1, 2). To date, molecular dynamics (MD) simulation represents a powerful tool to deal with cluster ions theoretically (Ref 3, 4). For instance, MD simulation has been adopted to simulate the radiation effect on mechanical properties of copper nanowires and reveals that yield strength decreases after radiation (Ref 5). Moreover, the generation of defects by radiation is simulated at picosecond scale, while they are annihilated at grain boundaries at microsecond scale (Ref 6-8). It is also found that defects in bulk can migrate to surface and vacancies and aggregate together after radiation, forming pores, which make materials brittle. On the other hand, vacancies, which are pinned at grain boundaries of nanomaterials, can be annihilated by interstitial atoms, giving rise to the self-healing of nanomaterials (Ref 6, 9).
Yong Chen, Liangbin Hu, Changjun Qiu, and Bin He, School of Mechanical Engineering, University of South China, Hengyang 421001, PeopleÕs Republic of China; and Zhongchang Wang, International Iberian Nanotechnology Laboratory (INL), Avenida Mestre Jose Veiga, 4715-330 Braga, Portugal. Contact e-mails: [email protected]
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