Structural and hydriding properties of the intermetallic Y1-xNi2 synthesized by mechanical alloying or submitted to mechanical grinding

The sample 'YNi2' and the powder mixture (Y+2 Ni) were submitted to a milling process under an argon atmosphere. X-ray powder diffraction and microprobe analysis revealed the formation of the phase Y0.97Ni2 by mechanical alloying (MA). This compound, after a heat treatment at 823 K, decomposes into two phases having the following Formula composition: Y0.92Ni2 and YNi1.84. The hydriding propel-ties were studied at T=373 K and P-H2 = 1.1 MPa; it absorbs congruent to 3 H mol(-1) and decomposes into four phases: yttrium hydrides YH2 and YH3, Ni metal and an amorphous phase. The hydriding properties of the ground sample 'YNi2' were also studied, its hydrogen absorption capacity has increased at 373 K but only fur mechanical grinding (MG) performed for 3 h. X-ray diffraction did not reveal in this case any amorphization after hydrogenation at 373 K. (C) 2001 Elsevier Science B.V. All rights reserved.