In-situ SEM observations of crack nucleation and propagation in a notched tensile specimen of Ni{sub 3}Al with boron

Journal Article · Tue Apr 01 04:00:00 EST 1997 · Scripta Materialia

DOI:https://doi.org/10.1016/S1359-6462(96)00455-1· OSTI ID:460422

Xu, Y; Schulson, E M ^[1]

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1. Dartmouth College, Hanover, NH (United States). Thayer School of Engineering

Recently, the notch sensitivity of the ductile intermetallic alloy, Ni{sub 3}Al with boron, was studied by Xu and Schulson. It was found that when a thick specimen (thickness {ge} 1.4 mm) containing a sharp notch (Notch root radius {le} 0.04 mm) was strained, the material suffered from a loss of ductility: the reduction in area was reduced from about 33% to about 15% and the fracture mode changed from ductile transgranular to a 50/50 mixture of transgranular and intergranular. Experimental results and numerical simulation both suggested that cracks initiated around the notch tip where both the tensile stress and the plastic strain reached a maximum. The fracture mode in the near-notch-tip region was ductile transgranular, typical of boron-doped Ni-rich Ni{sub 3}Al. It was then concluded that intragranular crack nucleation was very likely associated with the high work-hardening rate of Ni{sub 3}Al which may be a consequence of its slip character and dislocation interactions. This paper continues the work on the notch sensitivity of ductile Ni{sub 3}Al. It addresses specifically the questions of the crack nucleation site with respect to the notch tip and the crack propagation path. To this end, the paper describes an in-situ SEM (scanning electron microscopy) deformation study of crack nucleation and propagation in notched Ni{sub 3}Al with boron.

• DOE Contract Number: FG02-86ER45260
• OSTI ID: 460422
• Journal Information: Scripta Materialia, Journal Name: Scripta Materialia Journal Issue: 7 Vol. 36; ISSN 1359-6462; ISSN SCMAF7
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
BORON ADDITIONS
CRACK PROPAGATION
CRACKS
FRACTURE PROPERTIES
INTERMETALLIC COMPOUNDS
NICKEL BASE ALLOYS
NOTCHES