Bulk amorphous Pd–Ni–Fe–P alloys: Preparation and characterization

Bulk amorphous alloys of Pd_xNi_yFe_80−x−yP₂₀ (25 ≤ x ≤ 60, 20 ≤ y ≤ 55, x + y ≥ 60) were prepared by a flux-melting and water-quenching method. Seven-mm diameter glassy rods of Pd₄₀Ni_40−xFe_xP₂₀ (0 ≤ x ≤ 20) were studied in greater detail. For these alloys, the difference between the crystallization and glass transition temperatures ranges from 102 K for x = 0 to 53 K for x = 20. In this composition range, the reduced glass transition temperature, T_rg, ranges from 0.66 to 0.57. The change in density upon crystallization ranges from 0.24 ± 0.04% for x = 0 to 1.33 ± 0.24% for x = 10. The partial molar volume of Fe in amorphous Pd₄₀Ni_40−xFe_xP₂₀ alloys is significantly larger than the molar volume of (metastable) fcc Fe. This, as well as a comparison with the molar volumes of crystalline compounds, suggests chemically selective Fe–Pd bonding in these glasses.