Short-range ordering in structural relaxation of an amorphous Fe32Ni36Cr14P12B6 alloy

Abstract

Short-range ordering and its kinetics in the structural relaxation of an amorphous Fe32Ni36Cr14P12B6 alloy are studied by measurement of electrical resistance. When the specimens are annealed below 250 °C, the resistance rises and its temperature coefficient (TCR) decreases, while the resistance is reduced and the TCR increases when annealed above 250 °C. This fact is analyzed through the change of structure factor using Nagel’s approach for amorphous metals based on the extended Ziman theory. This analysis indicates that the structural relaxation can be classified into two types of short-range rearrangement of atoms; a chemical short-range ordering (CSRO) and a topological short-range ordering (TSRO). Consequently, it can be concluded that the structure factor S(K) at K=2kF increases when CSRO is formed, whereas it decreases in the progress of TSRO and the cause is attributable to the difference in the second moment of the atomic-level internal stress distribution 〈p2〉 in both states. Furthermore, the kinetics in the formation of the CSRO are analyzed on the assumption that the relaxation time obeys logarithmic normal distribution and from there the distribution width and the mean activation energy are determined to be 3.4 and 1.83 eV, respectively.