Fatigue damage in aluminium single crystals. 1: On the surface containing the slip Burgers vector

Journal Article · Sun Oct 01 04:00:00 EDT 1995 · Acta Metallurgica et Materialia

DOI:https://doi.org/10.1016/0956-7151(95)90165-5· OSTI ID:116128

Zhai, T; Martin, J W; Briggs, G A.D. ^[1]

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1. Univ. of Oxford (United Kingdom). Dept. of Materials

An aluminum single crystal with the axial direction of [25{bar 1}] was fatigued in push-pull at the constant resolved shear stress amplitude 4 MPa, frequency 20 Hz and room temperature. Microcracks, microvoids, macrobands, extrusions and intrusions were observed on the side-surface containing the Burgers vector b. Most microcracks were opened, and were within, but approximately perpendicular to, PSBs. Slip steps were found in the extrusions and intrusions. There was net irreversible slip in one direction in most PSBs. Some short cracks along the PSBs on the side-surface were also observed at 5 {times} 10{sup 6} cycles. These observations indicate that, without the aid of the surface roughness of PSBs, cracks can still be nucleated, and that, apart from the notch effect of a PSB, there are other factors controlling crack initiation in single crystal aluminum. There may be an internal tensile stress existing in a PSB in the direction of b, and a shear stress applied by the specimen grips in the specimens due to the irreversible slip in one direction in PSBs. These stresses and the applied stress are responsible for the formation of microcracks, microvoids, extrusions, intrusions and macrobands on the side-surface.

• OSTI ID: 116128
• Journal Information: Acta Metallurgica et Materialia, Journal Name: Acta Metallurgica et Materialia Journal Issue: 10 Vol. 43; ISSN 0956-7151; ISSN AMATEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM
CRACK PROPAGATION
CRACKS
DEFECTS
FATIGUE
MICROSTRUCTURE
NUCLEATION
ROUGHNESS
SHEAR PROPERTIES
SLIP
STRESSES
SURFACES
TENSILE PROPERTIES
VOIDS