In-situ TEM/heavy ion irradiation on ultrafine-and nanocrystalline-grained tungsten: Effect of 3 MeV Si, Cu and W ions

Abstract

Plasma facing components for future fusion applications will experience heliumand neutron-induced structural damage. Direct observation of the in-situ dynamic response of such components during particle beam exposure assists in fundamental understanding of the physical phenomena that give rise to their irradiation resistance. We investigated the response of ultrafine and nanocrystalline-grained tungsten to 3 MeV heavy ion irradiations (Si 2+ , Cu 3+ and W 4+) for the simulation of neutron-induced damage through transmutation reactions via in-situ ion irradiation-transmission electron microscopy experiments. Defect densities as a function of irradiation dose (displacement per atom) and fluence were studied. Four stages of defect densities evolution were observed, as a function of irradiation dose: 1) increase in defect density at lower doses 2) higher defect production rate at the intermediate doses (before saturation), 3) reaching the maximum value, and 4) drop of the defect density in the case of W 4+ , possibly due to defect coalescence and grain boundary absorption of small defect clusters. The effect of grain size on defect densities were investigated and found that defect densities were

Interaction of radiation-induced defects with tungsten grain boundaries at across scales: a short review

“…They speculated that the SIA-V annihilation in the bulk is the dominant process, which seems to contract our intuition. OKMC simulations by El-Atwani et al [11] suggest that the average V/SIA concentration in the bulk decreases with the decreasing of the grain size at 1050 K, while the Cu 3+ irradiation experiments at room temperature give a reverse trend [7].…”

“…Among the methods, engineering the material with a high density of defects sinks, e.g. grain boundaries (GBs) in nano-crystalline (NC) metals, was demonstrated to be one of the effective options to suppress the accumulation of radiation-defects and thus mitigate the radiation damage in W [4][5][6][7][8][9][10][11] and in other metals [12][13][14][15][16]. For instance, neutron irradiation experiments at 873 K suggest that the density of voids in NC W (equiaxed grain sizes of 50-200 nm) is much smaller than that in pure commercial W (an average grain size of 20 μm) [5].…”

Evaluation of helium effect on ion-irradiation hardening in pure tungsten by nano-indentation method

“…Since the armor and first wall will receive both high neutron irradiation and high heat flux, researches on irradiation effects on W at a wide variety of temperatures have been conducted so far: microstructure evolution under self-ion irradiation [1][2][3] , alien heavy ion irradiation [2,4,5] and helium [6][7][8] or deuterium-ion implantations [9] . Special attention was paid to the recrystallization effects on the formation of irradiation-induced microstructures as recrystallization may occur in the materials after suffering high heat load during operation.…”

Influence of laser shock peening on irradiation defects in austenitic stainless steels

“…It is expected that the irradiation defect clusters will migrate to and be annihilated at these sinks. For example, nanocrystalline metals of tungsten (W), nickel (Ni), and 304L stainless steels exhibit a higher radiation tolerance than their bulk counterparts due to an increased density of grain boundaries [15][16][17]. Multilayer nanocomposites with immiscible interfaces, such as iron/silicon oxycarbide (Fe/SiOC), copper/niobium (Cu/Nb), and vanadium/silver (V/Ag), can effectively mitigate radiation-induced swelling and a loss of mechanical integrity [18][19][20][21].…”