Dynamic strain aging and crack propagation in the 2091 Al-Li alloy

Journal Article · Wed Dec 01 04:00:00 EST 1993 · Scripta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-716X(93)90323-K· OSTI ID:5791616

Delafosse, D; Kubin, L P ^[1]; Lapasset, G ^[2]

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1. CNRS-ONERA, Chaetillon (France). Div. Leclerc
2. ONERA, Chaetillon (France). Div. Leclerc

Dynamic strain aging (DSA) phenomena, which stem from the dynamic interaction of mobile dislocations and diffusing solute atoms, are observed in many dilute alloys at intermediate temperatures. In uniaxial deformation, DSA may lead to a negative strain rate sensitivity (SRS) of the flow stress and to the occurrence of jerky flow, alias the Portevin-Le Chaetelier (PLC) effect. As little is known to date about the influence of DSA and the PLC effect on fracture-related properties, the aim of the present study is to investigate ductile fracture in a commercial Al-Li alloy, the 2091 alloy. In the standard treatment conditions used all through this work, this alloy exhibits serrated yielding in uniaxial deformation, associated with a depletion of the SRS. The present study is, therefore, focused on properties related to one single heat treatment, for which fracture is purely intragranular. Experimental results are reported and discussed on the influence of strain rate and temperature on both uniaxial deformation and the tearing behavior of the 2091 alloy. Evidence is found for an anomalous behavior of the tearing resistance in the temperature domain where DSA occurs. Further, heterogeneous deformation is shown to take place in such conditions in the plastic zone ahead of the crack tip region.

• OSTI ID: 5791616
• Journal Information: Scripta Metallurgica et Materialia; (United States), Journal Name: Scripta Metallurgica et Materialia; (United States) Vol. 29:11; ISSN 0956-716X; ISSN SCRMEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
360103 -- Metals & Alloys-- Mechanical Properties
AGING
ALLOYS
ALUMINIUM ALLOYS
ALUMINIUM BASE ALLOYS
CRACK PROPAGATION
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DEFORMATION
DISLOCATIONS
DUCTILITY
LINE DEFECTS
LITHIUM ALLOYS
MECHANICAL PROPERTIES
STRAINS
TENSILE PROPERTIES