| Budget Amount *help |
¥2,730,000 (Direct Cost: ¥2,100,000、Indirect Cost: ¥630,000)
Fiscal Year 2014: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2013: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
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| Outline of Final Research Achievements |
TiFe intermetallic, a candidate for hydrogen storage, does not absorb hydrogen easily because of difficult activation, while TiFe processed by HPT absorb hydrogen. We showed that the activation is due to (i) enhanced diffusion, (ii) surface segregation of Fe-rich islands and (iii) formation of grain boundaries.
To investigate the importance of grain boundaries, TiFe was processed by 4 routes. The annealed sample, with micrometer grain sizes, didn't absorb hydrogen. The groove-rolled sample, with submicrometer subgrain sizes, was partially activated. The HPT-processed and ball-milled samples, with nanograins, were fully activated. Therefore, the activation becomes easier when nanograins form.
Mg2Ni intermetallic was also processed by HPT and its hydrogenation was examined. While Mg2Ni after annealing absorbed hydrogen partially, the HPT-processed sample fully absorbed hydrogen at 423 K. It was concluded that the large fractions of grain boundaries are responsible for activation.
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