Rapid solidification and crystallization of a Zr-24at.% Fe alloy

Abstract

Rapidly solidified ribbons of Zr-24at.% Fe alloy produced in a melt-spinning apparatus have been found to contain a crystalline phase (which is base-centred orthorombic with lattice parameters a=30320 Å , b=10.980 Å and c=80800 Å ) in an amorphous matrix. This phase is believed to be the Zr3Fe intermetallic compound which is produced through diffusionless solidification from a melt of the some composition. The morphologies of crystalline particles which are present as isolated crystals or as aggregates of contiguous particles in the amorphous matrix are described and their possible mode of formation discussed. The origin of different types of interface between these crystals and the amorphous matrix is discussed in terms of solute rejection. The phase formed after crystallization in the amorphous matrix was identified as the orthombic Zr₃Fe phase. The morphology and distribution of the crystals originating from the amorphous phase were examined and compared with those formed during solidification. The effects of pre-existing crystals in the amorphous matrix during the crystallization process are discussed. The crystallization process was studied at two temperatures, -598 and 723 K. Crystallization at the lower temperature was found to be associated with significant growth of the pre-existing crystals. Extensive nucleation of the crystalline phase in the amorphous matrix followed by a limited growth culminating in early impingement marked the crystallization process at the higher temperature.