On short range order and micro-domains in the Ni4Mo system

The initial stages of ordering in Ni3Mo and Ni4Mo have been investigated by transmission electron microscopy and diffraction. The development of long‐range order in Ni3Mo is associated with decomposition into the two metastable phases Ni2Mo and Ni4Mo, which are eventually replaced by the equilibrium Ni3Mo at a later stage of ordering. Evidence for the presence of metastable Ni2Mo phase was also found during the early stages of ordering of Ni4Mo. The presence of the metastable phase Ni2Mo at Ni4Mo composition and that of Ni2Mo and Ni4Mo at Ni3Mo composition can be explained in terms of the recent thermodynamic calculations of the ground states of ordered binary alloys by Cahn and his co‐workers.

“…8), one may question why this ,structure is not observed as a metastable phase. It has been shown earlier [8,13] that the presence of {1-~0} s ro spots in Ni-Mo r …”

Section: ( 5)mentioning

confidence: 94%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

The metastable phase Ni2Mo and the initial stages of ordering in NiMo alloys

Das

Thomas

1974

The mechanism of ordering in Ni3Fe: Modular ordering

Taunt

Ralph

1974

A detailed investigation of the mechanism of ordering in a Ni3Fe alloy has been carried out. The microstructure of the alloy in various partially ordered states was characterised on an atomic scale by field‐ion microscopy, and the absence of any two‐phase structure at any time in the reaction suggests that the nucleation and growth ordering mechanism is not operative. The modulations in the local degree of order, which are present during a continuous ordering reaction, were measured as a function of annealing time with a field evaporation technique. It was found that the quenched alloys contained well defined local order modulations which increased in wavelength linearly with annealing time. The “modular ordering” mechanism is introduced and shown to be in accord with this behaviour.

The DO22 Intermediate Phase in the Ni-Mo System

Tendeloo¹,

Ridder²,

Amelinckx

1975

A study of Ni3Mo by electron microscopy and electron diffraction reveals the presence of a new metastable intermediate phase during the early stages of ordering. This phase having the DO22 structure is only observed under well specified experimental conditions; it is generated immediately from the short range ordered state. The presence of this intermediate phase could be expected from a theoretical point of view, since none of the well known ordered phases as Ni4Mo, Ni3Mo, or Ni2Mo may form immediately from the f.c.c. high temperature phase. The DO22 phase is described here as an intermediate step in the quite complicated formation of ordered Ni3Mo.