scholarly journals Improvement of the fatigue crack-growth property by grain-boundary reaction precipitates at high temperatures.

1988 ◽  
Vol 54 (503) ◽  
pp. 1317-1321 ◽  
Author(s):  
Hiroshi IIZUKA ◽  
Manabu TANAKA ◽  
Humio ASHIHARA
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Grain Boundary ◽  
Crack Growth ◽  
High Temperatures ◽  
Growth Property ◽  
Boundary Reaction

Interfacial Composition Measurements in Complex Ni-Base Superalloys

1996 ◽  
Vol 458 ◽  
Author(s):  
E. L. Hall ◽  
J. Bentley
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Grain Boundary ◽  
Crack Growth ◽  
Time Dependent ◽  
Alloying Elements ◽  
Second Phase ◽  
Slow Cooling ◽  
X Ray ◽  
Boundary Composition

ABSTRACTIn this study, three different Ni-base superalloy / heat treatment combinations are studied in an attempt to assess the role of grain boundary morphology, composition, and phase distribution on mechanical properties, particularly time-dependent fatigue crack growth. The alloys chosen include one in which crack growth can be slowed by slow-cooling, and one in which crack growth is slow in the fast-cooled state. Both x-ray spectroscopy and energy-filtered imaging in the analytical electron microscope were used to measure grain boundary composition. The x-ray spectroscopy showed some enhancement of Cr, Mo, and W in the γ matrix at grain boundaries in the fast-cooled state, which was not present after slow cooling. Energy-filtered imaging showed no significant enhancement in alloying elements at interfaces in any of the samples studied. The results did show the tendency for the γ matrix to quickly equilibrate by second-phase precipitation, and a preference to avoid γ ‘- γ’ interfaces. The conclusions of this study are that time-dependent fatigue crack growth behavior in these alloys cannot be completely explained on the basis of grain boundary composition of major alloying elements.

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