Pressure dependence of hydrogen-induced amorphization in C15 Laves phase ErFe2

Abstract

Abstract C15 Laves phase ErFe 2 was thermally analyzed using a pressure differential scanning calorimeter (PDSC) in a hydrogen atmosphere. Hydrogen absorption in a crystalline state, hydrogen-induced amorphization (HIA), precipitation of ErH 2 in the amorphous phase and decomposition of the remaining amorphous phase into α-Fe and ErH 2 occurred exothermally with increasing temperature above 2.0 MPa H 2 in the same way as the other RFe 2 . HIA and precipitation of ErH 2 occurred simultaneously in 1.0 MPa H 2 . On the contrary, hydrogen absorbed crystalline (c-) ErFe 2 H 3.6 decomposed directly into α-Fe+ErH 2 below 0.5 MPa H 2 without formation of an amorphous phase. A reason why HIA is observed above the critical hydrogen pressure is discussed on the basis of the hydrogen content in crystalline c-ErFe 2 H x .