Structure study on rapidly solidified hydrogen storage alloy Zr(NiM)_2.1

摘要

Molten alloy Zr(NiM)_2.1 (M=Mn, Cr, V) israpidly solidified by melt spinning method with cooling rates ofalloy ribbons between 1.35X10~5 Ks~-1 and 5.33X10~6 Ks~-1.The structure is analyzed by means of XRD and TEM. The datafrom XRD are further analyzed by the Rietveld method. The resultsshow that all the rapidly solidified allooys with different coolingrates are composed only of micro-crystalline C14 Laves and C15Laves phases, different from theappearance of the non-Laves phaseconstituents Zr_7M_10 and Zr_9Ni_11 together with the C14 andC15 Laves phase in the slowly cooled master alloy. The C14 Lavesphase in rapidly solidified alloys assumes a laminar structure, inwhich the dimensions of C14 laves micro-crystallites are almostconstant, 1 nm along the c dirction and 3-4 nm along the a and bdirections. The abundance of C14 Laves phase increases in rapidlysolidified alloys as the cooling rate increases, and on the contrary,the abundance of C15 Laves phase decreases. When the coolingrate increases from 4.35X10~5 Ks~-1 to 5.33X10~6 Ks~-1, theabundance of C15 Laves phase decreases from 88.29 wt . percentto 43.36 wt. precent, and the crystallite size of C15 phasedecreases from 54.1 nm to 17.8 nm. 1999 Elsevier Science S.A.All rights reserved.