Effects Of Rare Earth On Structure And Electrochemical Performance Of V-Based Solid Solution Alloys

In this paper, Ti_0.25V_0.35Cr_0.2Ni_0.2 and Ti_0.17Zr_0.08V_0.35Cr_0.1Ni_0.3 are selected as referential alloys, and rare earth elements such as La, Ce, Pr, Nd and Mm have been added in them. The effects of the rare earth on V-based solid solution alloys have been investigated and the alloys with better integral performances for being used as the anode of MH-Ni have been obtained.The alloy samples are prepared by the non-selfconsumable vacuum arc melting. By means of XRD, SEM-EDS and electrochemical tests, the structure and electrochemical properties of the alloys have been investigated.It is shown that the double phase structure of the alloy with V-based solid solution as the main phase is not changed after adding rare earth elements. It is demonstrated by SEM-EDS that RE cannot dissolve into both of the bcc phase and secondary phase, but form a new phase with some other metallic elements. After adding rare earth elements, the activating ability of the alloy electrode is improved, but the charge retention ability is aggravated. The alloy electrode is sensitive to temperature. La, Nd and Mm can enhance the high-rate discharge- ability (HRD) of Ti_0.17Zr_0.08V_0.35Cr_0.1Ni_0.3 alloy electrode. The P-C-T curves for Ti_0.17Zr_0.08V_0.35- Cr_0.1Ni_0.3 and Ti_0.17Zr_0.08V_0.35Cr_0.1Ni_0.3Mm_0.01 alloys have been depicted by electrochemical methods. It is shown that as temperature rises, the hydrogen equilibrium pressure of the alloys goes up, but the hydrogen desorbing performance deteriorates. After addition of Mm, the hydrogen equilibrium pressure of the alloy comes down, and the hydrogen desorbing performance meliorates. In conclusion, Ti_0.17Zr_0.08V_0.35Cr_0.1Ni_0.3La0.015 and Ti_0.17Zr_0.08V_0.35- Cr_0.1Ni_0.3Mm_0.01 show very good integral performances.