Plastic Strain Localization in Superalloy Single Crystals

Nickel-base superalloys are notorious for their inhomogeneous deformation and poor fatigue behavior. Previous studies that the slip was 'planar' or, equivalently, 'coarse' , independent of alloy composition. In this research, single crystal nickel alloys of various gamma prime vo...

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Bibliographic Details
Main Authors: Anton,D L, Giamei,A F
Format: Report
Language:English
Subjects:
COMPRESSION
CRACKING(FRACTURING)
CYCLIC TESTS
FATIGUE LIFE
FATIGUE TESTS(MECHANICS)
GROWTH(GENERAL)
Mechanics
NICKEL ALLOYS
PE61102F
PLANAR STRUCTURES
PLASTIC DEFORMATION
POROSITY
SINGLE CRYSTALS
STRAIN RATE
STRAIN(MECHANICS)
SUPERALLOYS
WUAFOSR2306A1
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Summary:Nickel-base superalloys are notorious for their inhomogeneous deformation and poor fatigue behavior. Previous studies that the slip was 'planar' or, equivalently, 'coarse' , independent of alloy composition. In this research, single crystal nickel alloys of various gamma prime volume fraction and misfit were deformed under either monotonic or cyclic loading conditions are examined for slip distribution at very high magnification. The conclusion of this research was that the degree of slip localization in superalloys is decreased moderately by misfit and significantly by larger volume fractions of the strengthening gamma prime phase. This difference in behavior is reflected in the location of initiation sites. The alloys with more localized slip showed surface initiation. Attempts to understand the origin of such pores by changes in solidification or heat treatment parameters led to the conclusions that it was possible to influence pore size or the volume fraction porosity, but that some pores were always present. As a result, no enhancement of fatigue life was obtained, consistent with theory.