Onc. Uwakweh et al., Neutron diffraction and phase evolution of the mechanically alloyed intermetallic compound zeta-FeZn13, MET MAT T A, 31(11), 2000, pp. 2739-2745
High-energy ball milling with subsequent annealing is used to synthesize th
e intermetallic compound zeta -FeZn13. The mechanically alloyed phase in th
e as-milled state is determined to be nonequilibrium, or metastable. Transm
ission electron microscopy (TEM) studies show a highly defective microstruc
ture with undefined grain areas, and the alloy can be described as a mechan
ical mixture of elemental Fe and Zn, based on neutron diffraction measureme
nts. Characteristic stages associated with its transformation to the equili
brium state are identified based on differential scanning calorimetry (DSC)
measurements. The activation energies corresponding to these stages are 12
8, 202, and 737 kJ/mole, respectively, with increasing transformation tempe
ratures. The first stage is related to limited atomic diffusion or rearrang
ements, such as recovery, during thermal treatment, while the second stage
depicts continued recrystallization and long-range atomic diffusion leading
to a stable phase formation. The third and final stage marks structural de
composition of the equilibrium structure due to phase transition. Neutron d
iffraction of the equilibrium alloy confirmed that the structure is C2/m, w
ith lattice parameters of a = 13.40995 Angstrom, b = 7.60586 Angstrom, c =
5.07629 Angstrom, and beta = 127 deg 18 minutes. The atomic positions of Fe
and Zn compared well to reported values.