The crystallography of cleavage fracture in Al sub 3 Sc

Journal Article · Wed Apr 01 00:00:00 EST 1992 · Journal of Materials Research; (United States)

DOI:https://doi.org/10.1557/JMR.1992.0868· OSTI ID:7111444

Schneibel, J H; Hazzledine, P M ^[1]

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1. Metals and Ceramics Division, Oak Ridge National Laboratory, P. O. Box 2008, Oak Ridge, Tennessee 37831 (United States)

The intermetallic compound Al{sub 3}Sc is a trialuminide with the L1{sub 2} structure, which deforms easily in compression at room temperature, with yield stresses around 100 MPa. As shown by single crystal compression experiments, slip occurs on {l brace}111{r brace} planes. In tension Al{sub 3}Sc fractures transgranularly in a brittle manner. The predominant cleavage plane is {l brace}011{r brace}. In a scanning electron microscope (SEM) numerous cleavage steps, which are aligned in three major crystallographic directions, are observed. The fracture surfaces almost always show some microscopic waviness along the traces of intersecting slip planes. Regions that are flat within the experimental resolution of the SEM are only occasionally observed. Some of the cleavage steps consist of {l brace}111{r brace} or {l brace}001{r brace} planes, but others are not distinctly crystallographic. Plastic deformation involving dislocation motion or twinning may have occurred at these steps. Reactions among different types of steps are also observed. One type of cleavage pattern found is strikingly similar to the typical appearance of fracture surfaces of fcc or fcc related materials after stress corrosion cracking. However, this particular pattern is only rarely observed in Al{sub 3}Sc and can therefore not be taken as evidence for stress corrosion cracking in this material. Our observations indicate that an interpretation of cleavage fracture in Al{sub 3}Sc in terms of surface energies alone is unlikely to be successful. Similarly, any criterion that categorizes its fracture behavior into either fully brittle or fuly ductile is faced with difficulties. A full understanding of the fracture morphology of Al{sub 3}Sc will therefore require detailed atomistic simulations.

• DOE Contract Number: AC05-84OR21400
• OSTI ID: 7111444
• Journal Information: Journal of Materials Research; (United States), Vol. 7:4; ISSN 0884-2914
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM COMPOUNDS
FRACTURE PROPERTIES
SCANDIUM COMPOUNDS
CLEAVAGE
CRYSTALLOGRAPHY
DEFORMATION
DISLOCATIONS
INTERMETALLIC COMPOUNDS
SCANNING ELECTRON MICROSCOPY
TWINNING
ALLOYS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
ELECTRON MICROSCOPY
LINE DEFECTS
MECHANICAL PROPERTIES
MICROSCOPY
MICROSTRUCTURE
TRANSITION ELEMENT COMPOUNDS
360103* - Metals & Alloys- Mechanical Properties
360102 - Metals & Alloys- Structure & Phase Studies