ORDERING IN Ni₄Mo : AN APFIM/TEM/HVEM STUDY

Abstract
A combined atom probe field-ion microscopy, transmission electron microscopy and high voltage electron microscopy study has been performed to investigate the various ordering phenomena in a high purity Ni₄Mo alloy. A disordered material was produced by low temperature high voltage (1 MeV) electron irradiation to a dose of approximately 0.4 displacements per atom. No short range order was observed during the disordering of the long range ordered material. The disordered material was found to have a statistically random distribution of molybdenum. In-situ annealing experiments of the disordered material in the temperature range 300 to 700°C, revealed that SRO occurred prior to the LRO state. In short range ordered material produced by thermal annealing solution treated and quenched material, no statistical evidence for microdomains, clustering or a periodic composition fluctuation was observed with the atom probe.