Metal-hydride characterization avid mechanical properties of Ti-6Al-4V alloy

Hydrogen absorption/dessociation properties and mechanical properties were examined in a Ti-6Al-4V alloy exposed to highly pressurized hydrogen gets o f 0.1-5 MPa at elevated, temperatures of 373 K to 773 K. Pressure-Concentra tion-Temperature (P-C-T) test results of the materials exhibit a large amou nt of hydrogen absorption up to 3 wt% H at 473 K with plateaus as observed in typical hydrogen absorption materials and the specimens tested are broke n into pieces with the same level of hydrogen contents. Hydrogen dissociati on from the material is not observed below 773 K. The results of bending te sts and fractography show no degradation of mechanical properties of the ma terials with hydrogen contents of less than 0.1 wt% H. It is concluded from these test results that there is no mechanical degrada tion of Ti-6Al-4V vacuum vessel material for the tokamak device, JT-60SU du e to metal-hydride reaction between Ti-6Al-4V and fuel hydrogen induced by hydrogen absorption mechanism into Ti-6A1-4V under the hydrogen pressure of 0.01-1Pa H between room temperature and 773 K, in which JT-60SU is being d esigned, mainly because oxide layer formed on Ti-6Al-4V restrains metal-hyd rogen reaction into the material.