Structural relaxation in Pd-Cu-Ni-P metallic glasses

The structural relaxation process in the Pd₄₀Cu₃₀Ni₁₀P₂₀ and the Pd₄₃Cu₂₇Ni₁₀P₂₀ metallic glasses was examined by measuring the electrical resistivity at room temperature, ρ(300), and the endothermic peak behavior peculiar to glass transition after relaxation on the differential scanning calorimetry (DSC) curve. It was concluded that the annihilation and the formation of the free volume increased and decreased the ρ(300), respectively. The maximum change in ρ(300) due to the annihilation of the free volume was about 2% of that in the as-quenched sample. The relaxation process at 540K just below glass transition was investigated. The quenched-in free volume for a Pd₄₃Cu₂₇Ni₁₀P₂₀ glass did not reach the equilibrium value within annealing period of about 3.0×10⁶s. The local structure of the Pd₄₀Cu₃₀Ni₉⁵⁷Fe₁P₂₀ glass was examined by Mössbauer spectroscopy for the relaxation process at 540K. The average quadrupole splitting, Q-, and the isomer shift, δ-, decreased with time up to 1.44×10⁶s and thereafter these increased. The origin of this increase was not explained if we took account for the contribution of the chemical short range ordering process.