In situ determination of misorientation angle of grain boundary by field ion microscopy analysis

The shape of the emitter is of cardinal importance to field-ion microscopy. First, the field evaporation process itself is closely related to the initial tip shape. Secondly, the imaging stress, which is near the theoretical strength of the material and intrinsic to the imaging process, cannot be characterized without knowledge of the emitter shape. Finally, the problem of obtaining quantitative geometric information from the micrograph cannot be solved without knowing the shape. Previously published grain-boundary topographies were obtained employing an assumption of a spherical shape (1). The present investigation shows that the true shape deviates as much as 100 Å from sphericity and boundary reconstructions contain considerable error as a result.Our present procedures for obtaining tip shape may be summarized as follows. An empirical projection, D=f(θ), is obtained by digitizing the positions of poles on a field-ion micrograph.

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The Study of Grain-Boundary Segregation by Field-Ion Microscopy

Metal Science Journal ◽

10.1179/030634572790445911 ◽

1972 ◽

Vol 6 (1) ◽

pp. 111-112

Author(s):

D. A. Smith ◽

G. D. W. Smith

Keyword(s):

Grain Boundary ◽

Boundary Segregation ◽

Grain Boundary Segregation ◽

Field Ion Microscopy ◽

Ion Microscopy

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The Microchemistry of Grain Boundaries in Ni3Al

MRS Proceedings ◽

10.1557/proc-133-155 ◽

1988 ◽

Vol 133 ◽

Cited By ~ 10

Author(s):

D. N. Sieloff ◽

S. S. Brenner ◽

Hua Ming-Jian

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Atom Probe ◽

High Concentration ◽

Field Ion Microscopy ◽

Boron Clusters ◽

Ion Microscopy

ABSTRACTGrain boundary regions in B-doped as well as B-free Ni3AI were studied by field-ion microscopy and atom probe microanalysis. In the ductile, recrystallized, Ni-rich alloys the segregation of boron was often accompanied by an enrichment of nickel. Such an enrichment was not observed at boundaries in B-free alloys. Boron was also observed to segregate to the boundaries in a 25.2A1 - IB alloy which was reported to contain boron clusters. Such clusters were not observed, instead a high concentration of boron pairs were found.

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The influence of phosphorus in dilute solid solution on the absolute surface and grain boundary energies of iron

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1965.0158 ◽

1965 ◽

Vol 286 (1407) ◽

pp. 479-498 ◽

Cited By ~ 139

Keyword(s):

Solid Solution ◽

Grain Boundary ◽

Phosphorus Content ◽

Diffusion Creep ◽

Self Diffusion ◽

Thin Foils ◽

The Absolute ◽

Contractile Forces

A technique has been developed for the determination of the absolute surface energies of iron and iron alloys at temperatures of up to the melting point. The technique is based upon the measurement of the contractile forces in thin foils. All measurements are made in situ and chemical equilibrium is maintained throughout the experiment. The results show that phosphorus in dilute solid solution decreases progressively the surface energy of iron at 1450 °C from 2100 ergs cm -2 to 1200 ergs cm -2 , for increasing phosphorus contents of up to 0.36%. Results were also obtained for the γ phase in which the effect is less pronounced. Absolute grain boundary energies were also determined as a function of phosphorus content. From the strain rate of the foils which move by a diffusion creep mechanism, it was deduced that the self diffusion coefficient increases linearly with phosphorus content. Application of the Gibbs adsorption theorem has permitted the evaluation of the extents of equilibrium segregation of the solute to interfaces. The maximum levels are 2.3 x 10 -9 g-atom cm -2 at surfaces and 1.1 x 10 -9 g-atom cm -2 at grain boundaries. The relevance of these measurements to the problem of the intergranular brittle fracture of iron/phosphorus alloys is discussed.

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