Effect of Shaft Shoulder Diameter on Properties of Vanadium Titanium Nickel Hydrogen Storage Alloy Modified by Friction Stirring

Friction stirring modification experiments of V₃TiNi_0.56 hydrogen storage alloy with different shoulder diameters were carried out,and the microstructures and charge-discharge cycle stability were tested and compared.The results show that friction stirring modification can refine the grain size and improve the cycle stability of the alloy.When the shoulder diameter is at 8～12 mm,the average grain size and discharge capacity decay rate of the alloy decrease first and then increase,and the charge-discharge cycle stability of the alloy increases first and then decreases.Compared with the specimens without friction stirring modification,the average grain size of the alloy decreases by 48% and the discharge capacity decay rate decreases by 24% when the stirring head with a diameter of 10 mm is used for friction stirring modification.