Experiment Research On Wall Stress Induced By LaNi_5-xAI_x(x=0,0.3) Alloys Ab-/Desorption Cycles

The LaNi5Al series of alloy were selected as tritium storage and boost materials. The alloy lattice swells and compresses in the hydrogen ab-/desorption cycle The wall stress is induced as a result of ununiform deformation. The pulverization of the bulk material leads to self-packing and concentration of stress. By using strain gauge, we have researched the relations between the wall stress and 1) the number of hydrogen ab-/desorption cycle; 2) the capacity of hydrogen storage; 3) the packing fraction; 4) the thickness of the wall. The results showed that different locations on the wall exhibited greatly different levels of wall stress and the wall stress increased with the cycling of hydrogen ab-/desorption. The wall stress induced on the bed which had larger packing fraction and thinner wall increased more evidently. So the bed produced plastic deformation more quickly. There was a law between the wall stress and the capacity of hydrogen storage, which showed that the wall stress increased in varying degrees as hydrogen was added up to a bed loading of about 0.6 hydrogen to metal atom ratio. In addition we tentatively probed into the cause of the crack produced after ab-/desorption cycle and found out that the cause was hydrogen embrittlement induced by welding. Those researches were significant for evaluating the safety properties of the hydride storage bed.