Search

Ordering in alloys is a topic of growing technological and scientific interest within the field of materials science. This is because the advantageous high temperature and corrosion properties of intermetallic compounds are linked to the effect of long-range ordering. Ordering effects as observed by electrical resistometry are discussed in this paper with respect to stable states of order (thermal equilibrium) and the ordering relaxation kinetics leading from one stable state to another. Examples are given on CuPt (L11), CuAu (L10), Cu3Au (L12), Ni3Al (L12) and FeAl (B2). [Copyright &y& Elsevier]

A detailed investigation of long-range ordering (LRO) in anisotropic FePd by residual electrical resistivity showed considerable differences in the maximum degree of order between ordering in a cold-rolled state and a fully recrystallised state: A higher degree of order is achieved in the deformed state. This result can be explained by the different microstructures evolving in the undeformed (polytwinning) and the deformed state (discontinuous or ‘massive ordering’). [Copyright &y& Elsevier]

We present molecular dynamics simulations of ordering kinetics in the Ni3Al alloy performed within the embedded atom method (EAM) as a scheme for interatomic potentials. The simulation cell containing 1372 atoms was initially perfectly L12-long-range ordered. After having artificially created one vacancy by removing at random one Ni-atom, the dynamics of the system was simulated at constant temperature and pressure. Atoms are found to migrate predominantly via jumps to nearest-neighbour (nn) vacancies. The number of antisites is low in comparison to the total number of atomic jumps. Therefore most of the jumps are ineffective for ordering kinetics causing only temporary change of the chemical order. Accordingly, the jumps creating antisites are most often followed by reverse jumps. Antisite defects are created as nn antisite pairs. This result is in agreement with predictions based on a model originally formulated within Monte Carlo simulations. [Copyright &y& Elsevier]