Viscous Flow Workability of Ni-Cr-P-B Metallic Glasses Produced by Melt-Spinning in Air

Abstract

We prepared the Ni_80−xCr_xP₁₆B₄ (x=3, 6, 9, 12, 15, 18, 21, 24, 27 and 30 at%) alloy ingots in an Ar flow atmosphere and then produced the alloy ribbons by melt-spinning. The thermal stability was examined and the alloy composition was optimized.
A supercooled liquid state was observed in the alloys with Cr contents above 9 at% and the T_g and T_x increased with increasing Cr content. There is a tendency for ΔT_x to increase with increasing Cr content up to 18 at%. The largest ΔT_x is about 45 K and remains almost unchanged in the Cr content range above 15 at%. The groove-forming tests were performed for the alloy with optimized compositions. The Ni₆₅Cr₁₅P₁₆B₄ glassy alloy was heated up to T_g and was deformed by hot-pressing with dies in the supercooled liquid state. The alloy possessed a single glassy phase and the thermal stability parameters, T_g, T_x and ΔT_x of the alloy did not change even after the hot-pressing. Thus, the Ni-based glassy alloy was not thermally affected by the hot-pressing treatment in the present experimental condition. Finally, we successfully produced the metallic glassy separator for Proton Exchange Membrane Fuel Cell (PEMFC) by hot-pressing in the supercooled liquid state.