T.P. Gabb

Glenn Research Center, Cleveland, Ohio

J.W. Smith

Cleveland State University, Cleveland, Ohio

Microprobe Evaluations of Grain Boundary

Segregation in KM4 and IN100

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Glenn Research Center

T.P. Gabb

Glenn Research Center, Cleveland, Ohio

J.W. Smith

Cleveland State University, Cleveland, Ohio

Microprobe Evaluations of Grain Boundary

Segregation in KM4 and IN100
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Microprobe Evaluations of Grain Boundary Segregation in KM4 and IN100

T.P. Gabb and J.W. Smith

Superalloys; Disks; Grain boundaries; Segregation

Unclassified -Unlimited

Subject Category: 26 Distribution: Nonstandard

T.P. Gabb, NASA Glenn Research Center; and J.W. Smith, Cleveland State University, 1983 E. 24th Street,

Cleveland, Ohio 44115–2403. Responsible person, T.P. Gabb, organization code 5100, 216–433–3272.

Turbine disk alloys subjected to fatigue cycles with dwells at high temperatures and stresses can fail by cracking along

grain boundaries. This could be due to concentrated creep deformation or environmental attack at grain boundaries. It

would be important to identify any chemical segregation along grain boundaries to aid understanding of this intergranular

failure mode. The objective of this study was to evaluate the degree of chemical segregation present at the grain boundaries of two disk alloys, KM4 and IN100. An electron microprobe employing wavelength dispersive x-ray chemical

analyses was used to characterize the chemistry along multiple grain boundaries in metallographically prepared samples

of each alloy. Some degrees of boron, chromium, and cobalt enrichment of grain boundaries were observed in each alloy.