La-Mg-Ni system(PuNi_3-type) La_2Mg(Ni_(0.85)Co_(0.15))_9B_x(x=0,0.05,0.1,0.15,0.2) hydrogen storage
alloys were prepared by casting and
rapid quenching.The microstructures and electrochemical capacities of the as-cast and
quenched alloys were determined and measured.The effects of the
boron content and the
Quenching rate on the microstructures and electrochemical capacities of the alloys were investigated in detail.The obtained results show that the as-cast and quenched alloys have a multi-phase structure,composing of the(La,Mg) Ni_3 phase(PuNi_3 structure), the LaNi_5 phase and the LaNi_2 phase.A trace of the Ni_2B phase exists in the as-cast alloys containing
Boron.The Ni_2B phase in the alloys containing boron nearly disappears after rapid quenching.The effects of boron addition on the capacities of the as-cast and quenched alloys are different.The capacities of the as-cast alloys monotonously decrease with the increase in boron content,whereas the capacities of the as-quenched alloys have a maximum value with the change of boron content.The effects of rapid quenching on the capacities of the alloys with boron and without boron are different.The capacity of the alloy without boron monotonously decreases with increasing the quenching rate,whereas the capacities of the alloys with boron have a maximum value with the change of the quenching rate.