Creation of Intelligent Materials with a Resistance to Beam-Impact and Radiation Damage

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The present work has been performed to develop intelligent materials which have strong resistance to both beam impact (or shock-wave) and radiation damage. They are required for the beam target of an intense accelerator and space applications. Main results are as follows : (1)For the tungsten target, radiation-resistant, ultra-fine grained tungsten materials was successfully developed with a mechanical alloying method, dispersing TiC into tungsten. (2)The GBE (grain boundary engineering) controlled stainless steels were developed for the purpose to overcome an inter-granular corrosion which occurs in a heat affected zone of a weld material. (3)As a coating technique for tungsten target, CrN film formation with the molten salt method has been attained to be several micro-meter thickness. (4)For liquid mercury target, synergistic effect of C and N plasma surface treatment to suppress pitting damage was prominent. High-speed camera clarified bubble behavior near mercury/glass window surfa … More ce and gave a clue of pitting problem. (5)To space application, we developed the tough AIN-TiN composite material and the intelligent material composed of niobium and aluminum that has an intelligence to stop propagation of micro-cracks created by debris attack. (7)Rapid cooling test of tantalum-clad tungsten plate fabricated with the HIP method for MW-class spallation target showed that the plate was not broken and will be endurable even in case of loss-of-coolant accident. (8)Positron lifetime measurement clarified no effect of GBE to defect formation, and did irradiation effects. (9)Post irradiation experiments for STIP-II samples which had been irradiated at the spallation target of the SINQ facility at Paul Scherrer Institut showed that the JPCA, stainless steel (SS) produced in Japan had elongation above 3 dpa, while the SS-316 irradiated at LANSCE lost elongation above 3 dpa. Future tasks are to collect more experimental data of damages, to progress a theoretical investigations and develop the simulation code system, and to develop essentially strong materials. Less