The Hydrogen Absorption And Desorption Properties Of V-Ti-Cr-Fe Alloys

In this thesis, literatures in the related academic domain were summarized and analysed. Based on the V-Ti-Cr systems and the abundant VTi and VFe resources in Panzhihua of Sichuan Province,V-Ti-Cr-Fe systems with low cost and independent patent were developed. The influence of composition on the alloys'properties was studied by method of uniformity design and adjusting Ti/(Cr+Fe),Cr/Fe,Ti/Cr and V content. Heat treatments on the structures, hydrogen absorption and desorption properties of V-Ti-Cr-Fe alloys were researched. The effects of substituting of Ni or Mn for V on the properties and microstructure of V-Ti-Cr-Fe alloys were investigated and the cyclic properties of hydrogen absorption and desorption in the optimized alloys were also discussed.The main results are presented as follows:(1) V-Ti-Cr-Fe alloys were investigated through controlling Ti/(Cr+Fe),Cr/Fe,Ti/Cr and V content. The main phase was BCC structure when Ti/(Cr+Fe)>1. When Ti/(Cr+Fe)<1 there existed TiFe2,TiCr2 andσphase FeCr. For V30Ti35Cr35-xFex (x=5,7.5,10,11.2,12.5), the farther the Cr/Fe deviated from 2.5, the smaller the alloy's effective hydrogen capacity became. To V30Ti31+xCr39-xFe10 ,when the ratio of Ti/Cr was increased, the hydrogen absorption capacities increased while the hydrogen desorption pressure decreased, and the hydrogen desorption capacities decreased when the ratio of Ti/Cr was more than 1.2. To Vx(TiCrFe)100-x(Ti:Cr:Fe=7:5:2), when content of V was increased, both the hydrogen absorption and desorption capacities increased while the desorption pressure decreased. Laves phase appeared in the alloy containing 20at% V.