Grain-Boundary Chemistry and Intergranular Fracture in Austenitic Nickel-Base Alloys—A Review

CORROSION ◽  
1990 ◽  
Vol 46 (4) ◽  
pp. 319-330 ◽  
Author(s):  
G. S. Was
Keyword(s):  
Grain Boundary ◽  
Intergranular Fracture ◽  
Nickel Base ◽  
Boundary Chemistry

A Comparison of Grain Boundary Monolayer Segregation Measurements Made Using Fegstem and Auger Spectroscopy

1996 ◽  
Vol 439 ◽  
Author(s):  
S. B. Fisher ◽  
P. Spellward ◽  
R. Scowen ◽  
B. Lee
Keyword(s):  
Grain Boundary ◽  
Boundary Data ◽  
Auger Spectroscopy ◽  
Theoretical Description ◽  
Electron Optics ◽  
Highly Active ◽  
Active Electron ◽  
Nickel Base ◽  
Boundary Chemistry ◽  
The Relationship

AbstractThe active electron optics suite at Magnox Electric's Berkeley Centre has a VG HB501 FEGSTEM and a FE-sourced Auger Microprobe (a Fisons Microlab-F) which are routinely used for grain boundary chemistry studies in a variety of highly active austenitic and ferritic steels and nickel base alloys.In a number of investigations sufficient grain boundary data have been obtained to allow a meaningful comparison between the two instruments to be made. It has been established that for the overwhelming majority of materials and conditions there exists a reasonable correlation between the two sets of compositional (on-boundary) data.This paper presents this correlation and gives a simple theoretical description justifying the relationship between the raw data from the instruments. Examples are given of materials and conditions for which the correlation cannot be established and this leads to a discussion of the usefulness of the availability of the correlation.

Intergranular fracture and grain boundary chemistry of Ni3Al and Ni3Si

1985 ◽  
Vol 19 (4) ◽  
pp. 551-556 ◽  
Author(s):  
T. Takasugi ◽  
E.P. George ◽  
D.P. Pope ◽  
O. Izumi
Keyword(s):  
Grain Boundary ◽  
Intergranular Fracture ◽  
Boundary Chemistry

Effect of grain boundary chemistry on the intergranular fracture of iron at cathodic potentials

1981 ◽  
Vol 12 (9) ◽  
pp. 1621-1629 ◽  
Author(s):  
R. H. Jones ◽  
S. M. Bruemmer ◽  
M. T. Thomas ◽  
D. R. Baer
Keyword(s):  
Grain Boundary ◽  
Intergranular Fracture ◽  
Boundary Chemistry

Brittle fracture and grain boundary chemistry of microalloyed NiAl

1990 ◽  
Vol 5 (4) ◽  
pp. 754-762 ◽  
Author(s):  
E. P. George ◽  
C. T. Liu
Keyword(s):  
Solid Solution ◽  
Yield Strength ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Intergranular Fracture ◽  
Fracture Mode ◽  
Tensile Ductility ◽  
Hard Sphere Model ◽  
Strengthening Effect ◽  
Boundary Chemistry

The room-temperature tensile properties, fracture mode, and grain boundary chemistry of undoped stoichiometric NiAl, as well as NiAl doped with boron, carbon, and beryllium, have been investigated, Pure, stoichiometric NiAl fractures with limited tensile ductility in a predominantly intergranular manner. Auger analyses revealed that the grain boundaries in NiAl are extremely clean and free of any segregated impurities, indicating that they are intrinsically brittle. Boron, when added to stoichiometric NiAl at a bulk level of 300 wt. ppm, segregates to the grain boundaries and suppresses intergranular fracture. However, there is no attendant improvement in tensile ductility because boron is an extremely potent solid solution strengthener in NiAl, more than doubling its yield strength. As a result, any potential benefit of improving grain boundary strength is more than offset by the increase in yield strength. Unlike boron, both carbon (300 ppm) and beryllium (500 ppm) are ineffective in suppressing intergranular fracture in NiAl, and Auger analyses of the C-doped alloy revealed that carbon did not affect the fracture mode because it did not segregate to the grain boundaries. Although neither beryllium nor carbon suppressed grain boundary fracture, their effects on the tensile ductility of NiAl were quite different: the ductility of the Be-doped alloy was higher than that of the B-doped alloy because beryllium, unlike boron, has a rather modest strengthening effect in NiAl, whereas the C-doped alloy was brittle like the B-doped alloy, because carbon is a potent solid solution strengthener, just like boron. These observations were rationalized by considering a hard-sphere model for interstitial and substitutional sites in NiAl. It was concluded that boron and carbon occupy interstitial sites, whereas beryllium dissolves substitutionally. In all the alloys that were investigated, the Ni and Al contents of the grain boundaries were not significantly different from the bulk levels, and no evidence was found for B–Ni cosegregation.

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