skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Serrated yielding in Al-Li alloys

Abstract

Serrated yielding (SY) during tensile testing has been observed in Al-Li alloys, both in the binary and the commercial quaternary alloys, in single crystal as well as polycrystalline materials. Serrated yielding is commonly explained by a dynamic strain aging (DSA) model developed by McCormick and van den Beukel. All the solute elements present in Al-Li alloys, viz., Mg, Cu and Li are known to give DSA and SY. Several researchers believe the DSA to be the cause of SY and they attribute the disappearance of SY simply to the removal of solute from the matrix with aging. However, this argument has serious flaws. The present paper examines this aspect critically. The authors concluded that Al-Li alloys the disappearance of serrated yielding at a certain stage of aging is not due to removal of the solute from the matrix but due to the change in the nature of the metastable [delta][prime] precipitates - from fine coherent shearable precipitates to larger noncoherent nonshearable precipitates - which prevents the formation of the deformation bands. The serrated yielding reappears with extensive over aging due to the dissolution of these precipitates in favor of the equilibrium precipitates. The equilibrium precipitates, being widely spaced, are ineffectivemore » in preventing the formation of deformation bands.« less

Authors:
;  [1]
  1. (Imperial Coll., London (United Kingdom))
Publication Date:
OSTI Identifier:
6518016
Resource Type:
Journal Article
Journal Name:
Scripta Metallurgica et Materialia; (United States)
Additional Journal Information:
Journal Volume: 28:9; Journal ID: ISSN 0956-716X
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM ALLOYS; MICROSTRUCTURE; SHEAR PROPERTIES; LITHIUM ALLOYS; MAGNESIUM ALLOYS; DEFORMATION; EXPERIMENTAL DATA; PRECIPITATION; TRANSMISSION ELECTRON MICROSCOPY; ZIRCONIUM ADDITIONS; ALLOYS; CRYSTAL STRUCTURE; DATA; ELECTRON MICROSCOPY; INFORMATION; MECHANICAL PROPERTIES; MICROSCOPY; NUMERICAL DATA; SEPARATION PROCESSES; ZIRCONIUM ALLOYS; 360103* - Metals & Alloys- Mechanical Properties; 360102 - Metals & Alloys- Structure & Phase Studies

Citation Formats

Kumar, S., and McShane, H.B. Serrated yielding in Al-Li alloys. United States: N. p., 1993. Web. doi:10.1016/0956-716X(93)90025-N.
Kumar, S., & McShane, H.B. Serrated yielding in Al-Li alloys. United States. doi:10.1016/0956-716X(93)90025-N.
Kumar, S., and McShane, H.B. Sat . "Serrated yielding in Al-Li alloys". United States. doi:10.1016/0956-716X(93)90025-N.
@article{osti_6518016,
title = {Serrated yielding in Al-Li alloys},
author = {Kumar, S. and McShane, H.B.},
abstractNote = {Serrated yielding (SY) during tensile testing has been observed in Al-Li alloys, both in the binary and the commercial quaternary alloys, in single crystal as well as polycrystalline materials. Serrated yielding is commonly explained by a dynamic strain aging (DSA) model developed by McCormick and van den Beukel. All the solute elements present in Al-Li alloys, viz., Mg, Cu and Li are known to give DSA and SY. Several researchers believe the DSA to be the cause of SY and they attribute the disappearance of SY simply to the removal of solute from the matrix with aging. However, this argument has serious flaws. The present paper examines this aspect critically. The authors concluded that Al-Li alloys the disappearance of serrated yielding at a certain stage of aging is not due to removal of the solute from the matrix but due to the change in the nature of the metastable [delta][prime] precipitates - from fine coherent shearable precipitates to larger noncoherent nonshearable precipitates - which prevents the formation of the deformation bands. The serrated yielding reappears with extensive over aging due to the dissolution of these precipitates in favor of the equilibrium precipitates. The equilibrium precipitates, being widely spaced, are ineffective in preventing the formation of deformation bands.},
doi = {10.1016/0956-716X(93)90025-N},
journal = {Scripta Metallurgica et Materialia; (United States)},
issn = {0956-716X},
number = ,
volume = 28:9,
place = {United States},
year = {1993},
month = {5}
}