10th Student Meeting of the Kanto-Koetsu Division of the Atomic Energy Society of Japan
開催地
和文:
東京
英文:
Tokyo
アブストラクト
Aluminum nitride (AlN) has outstanding properties of high thermal conductivity for about 170 to 220 W/m·K at 298 K and low thermal expansion for 4.3 to 4.6 x 10-6/K from 298 to 673 K are approximately comparable to silicon carbide (SiC) and leads to the expectation of using as radiofrequency window in nuclear application. Accordingly, this work aimed to study the effect of neutron irradiation on AlN properties and its recovery behavior under isochronal annealing.
AlN (Shapal, Tokuyama Soda Co. Japan) was neutron-irradiated in the Japan Materials Testing Reactor (JMTR) up to 4.4 x 1023 n/m2 (E > 0.1 MeV) at 573 K. The specimens were measured the macroscopic length change by a point-type micrometer at room temperature. The swelling of the specimens after irradiation was found for 0.139%. After that, the specimens were cut to bar shape with 2 x 2 x 25 mm size and both unirradiated and irradiated specimens were annealed by dilatometer up to 1673 K, heating rate 5 degree/minute, soaking at every 50 degree steps for 6 hours under helium gas flow 50 ml/min. Lattice parameter along a-axis and c-axis were increased 0.16% and 0.13% after irradiation and decreased 0.15% and 0.19% after annealing, respectively. Microstructure observation by SEM show the oxidation area on the surface for 15 to 20 microns’ thickness as related to XRD pattern of detected phases, AlN (JCPDS: 03-065-3409), and Al2O3 (JCPDS: 01-081-2266). Finally, the specimens were recovered under isochronal annealing. The result shows rapidly shrinkage at 423 to 523 K. Then, the specimen gradually shrank until 1573 K and started expanding in the higher temperature.
The neutron irradiation caused swelling and the expansion of lattice parameter both along a and c-axis. The isochronal annealing successfully recovered the length of the specimens up to 1573 K but caused the expansion at above temperature. However, the oxidized surface was occurred after annealing in high temperature.
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