High temperature fracture toughness of Ni{sub 3}Al alloy IC-396M

Conference · Thu Dec 31 04:00:00 EST 1992

OSTI ID:10132771

Alexander, D J

The fracture toughness of the nickel aluminide alloy IC-396M has been measured from room temperature to 800C. Material was tested in the as-cast condition. Specimens were oriented for crack growth either parallel or perpendicular to the dendritic structure (C-R and R-C orientations, respectively). Both orientations had acceptable levels of toughness from room temperature to 600C. At 650C the toughness decreased markedly with some recovery at 800C. Examination of the fracture surfaces revealed that the fracture mode changed from a ductile tearing mechanism at temperatures up to 600C to interdendritic fracture at 650C and higher temperatures. At 650C the crack grew along the dendrite axis for the C-R specimens, but for the R-C specimens the crack grew out-of-plane in attempting to follow the dendritic structure. It is believed that the presence of the sharp crack in the fracture toughness specimens allowed oxygen to penetrate to the crack tip, where straining exposed metal surfaces that were not protected by an oxide layer. The result was embrittlement of the interdendritic regions and low energy fracture, analogous to intergranular fracture in wrought materials.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 10132771
• Report Number(s): CONF-921101--97; ON: DE93008564
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103
ALUMINIUM ALLOYS
CRACK PROPAGATION
FRACTURE PROPERTIES
INTERMETALLIC COMPOUNDS
MECHANICAL PROPERTIES
NICKEL BASE ALLOYS
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
TEMPERATURE RANGE 1000-4000 K