1 © 2016 IOP Publishing Ltd Printed in the UK 1. Introduction Silicon carbide (SiC) is an important engineering material in nuclear energy systems due to its high-thermal conductivity, high-temperature stability, chemical inertness, and low neu- tron capture cross-section. Potential applications of the mate- rial include fuel cladding in gas-cooled reactors [1], irst wall in fusion reactors [2], and an inert matrix for transmutation of actinides [3]. Improvement of SiC in radiation resistance has important signiicance for those applications. Compared to the bulk counterparts, nanocrystalline materials with grain sizes below 100 nm have a great potential to exhibit improved radiation resistance. This is because there is a large frac- tion of grain boundaries (GBs) in nanocrystalline materials, which could act as eficient sinks for mobile point defects produced by irradiation. Enhanced irradiation resistance has been observed experimentally in many nanocrystalline mate- rials [4–9]. However, opposite experimental results were also reported in nanocrystalline materials including those that have exhibited enhanced irradiation resistance with a different grain size or under a different irradiation condition [10–15]. The reduced irradiation resistance with grain reinement could be attributed to the increased instability of the materials with increasing the volume fraction of GBs. Also, it may be caused Journal of Physics D: Applied Physics Grain growth of nanocrystalline 3C-SiC under Au ion irradiation at elevated temperatures Limin Zhang 1 , Weilin Jiang 2 , Amila Dissanayake 2 , Tamas Varga 2 , Jiandong Zhang 1 , Zihua Zhu 2 , Dehong Hu 2 , Haiyan Wang 3 , Charles H Henager Jr 2 and Tieshan Wang 1 1 School of Nuclear Science and Technology, Lanzhou University, Lanzhou, Gansu 730000, People’s Republic of China 2 Paciic Northwest National Laboratory, Richland, WA 99352, USA 3 Texas A&M University, College Station, TX 77843, USA E-mail: zhanglm@lzu.edu.cn and weilin.jiang@pnnl.gov Received 17 June 2015, revised 30 October 2015 Accepted for publication 11 November 2015 Published 9 December 2015 Abstract Nanocrystalline silicon carbide (SiC) represents an excellent model system for a fundamental study of interfacial (grain boundary) processes under nuclear radiation, which are critical to the understanding of the response of nanostructured materials to high-dose irradiation. This study reports on a comparison of irradiation effects in cubic phase SiC (3C-SiC) grains of a few nanometres in size and single-crystal 3C-SiC ilms under identical Au ion irradiation to a range of doses at 700 K. In contrast to the latter, in which the lattice disorder is accumulated to a saturation level without full amorphization, the average grain size of the former increases with dose following a power-law trend. In addition to coalescence, the grain grows through atomic jumps and mass transport, where irradiation-induced vacancies at grain boundaries assist the processes. It is found that a higher irradiation temperature leads to slower grain growth and a faster approach to a saturation size of SiC nanograins. This unusual behaviour could be associated with irradiation-induced grain nucleation and growth in amorphous SiC matrix in which the 3C-SiC grains are embedded. The results could potentially have a positive impact on structural components of advanced nuclear energy systems. Keywords: nanocrystalline 3C-SiC, ion irradiation, grain growth (Some igures may appear in colour only in the online journal) 0022-3727/16/035304+7$33.00 doi:10.1088/0022-3727/49/3/035304 J. Phys. D: Appl. Phys. 49 (2016) 035304 (7pp)