Investigation On The Structure And The Kinetic Properties Of Mg₂ Ni-type Hydrogen Storage Alloys

Based on research of the Mg₂Ni-type hydrogen storage alloys from both home and abroad, this paper established Mg₂Ni-type alloys as the research object. Mg₂₀Ni₍10-x0M_x(M=Co, Cu, Mn; x=1, 2, 3 ,4) alloys were designed. The alloy ingots were prepared using a vacuum mid-frequency induction furnace in a helium atmospherein in order to effectively prevent the volatilization of Mg. Part of the as-cast alloys was re-melted and spun by melt-spinning with a rotating copper roller to obtain the length of continuous, uniform thickness of the thin strip, as quenched alloys. Using XRD, SEM test alloys structure and morphology; with PARSTT2273 advanced electrochemical tester cast and quenched alloys of dynamic performance; with the PCT curve tester cast and quenched alloys of gaseous absorption hydrogen curve.The results showed that the substitution of Co for Ni did not change the major phase Mg₂Ni, but it led to the formation of MgCo₂ phase and Mg phase, and the amount of the MgCo₂ phase and Mg phase increases with the rising of Co content. The substitution of Co for Ni enlarge the cell volume of the alloys cleverly enlarged, and reduce the grain size of the alloys, leads to it significantly improved the hydrogen desorption capacity and the kinetics Properties. The Quenched treatment showed the presence of amorphous phase, And with the quenching rate increases, increasing the degree of amorphous, it leads to the alloy has a better performance of gaseous hydrogen absorption capacity and kinetics properties.The substitution of Cu for Ni did not change the phase Structure, still have a single-phase Mg₂Ni, and Cu elements dissolve with Mg₂Ni then solution and fully integrated into Mg₂Ni, till the hydrogen absorption capacity of the alloy is reduced while the Cu element increases, However, the substitution of Cu for Ni powder he alloy significantly, and reduce the grain size of the alloys, to improve the dynamic performance. The Quenched treatment not showed the amorphous phase, but appropriately improve its gaseous hydrogen absorption capacity and kinetics properties.The substitution of Mn for Ni make the phase Mg and a small quantity of phase MnNi come into existence of alloy,and with the rising of Mn content,the major phase Mg₂Ni cut down on, phase Mg and phase MnNi increase. The substitution of Mn for Ni enlarge the cell volume of the alloys cleverly enlarged, and reduce the grain size of the alloys, improve the dynamic performance, However, the amount of gaseous hydrogen with the increase of Mn content increases first and then decreases. The Quenched treatment showed the presence of amorphous alloy, and with the quenching rate increases, increasing the degree of amorphous, it leads to the performance of gaseous hydrogen absorption capacity and kinetics properties of alloy increase with the quenching speed increase .