The development of γ-γ′ lamellar structures in a nickel-base superalloy during elevated temperature mechanical testing

Enhancement of the High-Temperature Tensile Creep Strength of Monocrystalline Nickel-Base Superalloys by Pre-rafting in Compression

“…Over the last three decades, the effects of rafting on the creep behaviour have been discussed controversially in a number of papers [2,7,11,12,13,14]. It has to be mentioned that, in these investigations, all raft structures formed during tensile creep (for 6~0) and were oriented perpendicular to the stress axis.…”

Observations of directional gamma prime coarsening during engine operation

“…6), the thickness of the y 1 rafts were essentially the same thickness as the original y ' particles. However, the thickness of the rafted y was approximately three times its original thickness.…”

“…The thickness of the anomalous rafts compare closely t o the thickness of the original y 1 raft formation from the original y l . Therefore, the anomalous rafting had to occur during high cycle fatigue, cycle A, before normal rafting could occur in cycles 6 and C. Work performed by Nathal and MacKay (ref: 7) has shown that anomalous rafting occurs in the threaded grip sections of isothermal stressparticles, providing evidence of anomalous rupture samples where nonuniaxial stresses exist. rafting is therefore believed to be due t o an unknown complex stress at the surface of the blade during the high cycle fatigue engine test cycle.…”

Microstructure-Property Relationships in Directionally Solidified Single-Crystal Nickel-Base Superalloys

“…MacKay and Ebert (8,16,19) f u r t h e r extended t h e work o f Pearson by making q u a n t i t a t i v e measurements o f t h e r a f t development i n A l l o y 143 d u r i n g creep a t v a r i o u s temperatures and s t r e s s l e v e l s . The development o f r a f t i n g was examined f o r t h r e e d i f f e r e n t s t a r t i n g m l c r o s t r u c t u r e s ; F i g .…”