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Effect of cold compression on precipitation and conductivityof an Al–Li–Cu alloy
Author(s) -
KHAN A.K.,
ROBINSON J.S.
Publication year - 2008
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/j.1365-2818.2008.02116.x
Subject(s) - materials science , alloy , precipitation , nucleation , transmission electron microscopy , volume fraction , conductivity , electrical resistivity and conductivity , supersaturation , precipitation hardening , compression (physics) , hardening (computing) , phase (matter) , dislocation , metallurgy , composite material , analytical chemistry (journal) , thermodynamics , chemistry , nanotechnology , electrical engineering , chromatography , physics , engineering , layer (electronics) , organic chemistry , meteorology
Summary Transmission electron microscopy has been used to investigate the effect of increasing the degree of deformation applied by cold compression on the ageing kinetics and electrical conductivity response of an Al–Li–Cu alloy containing Mg and Ag. When cold compressed greater than 3%, the increased dislocation density accelerates the widespread precipitation of the T 1 phase resulting in an enhanced age hardening response. The lengthening rate of T 1 precipitates is also reduced in this cold compressed condition owing to the reduced local solute supersaturation, a result of the widespread precipitation of T 1 plates. Cold compression by less than 3% does not increase the age hardening response, and the precipitation of GP zones/θ″ appears to be suppressed. Precipitation of the T 1 phase is also not significantly enhanced compared with that of the more than 3% cold compressed conditions. The anomalous decrease in electrical conductivity is associated with the nucleation and growth of the T 1 phase. Strain fields around T 1 precipitates combined with the increased volume fraction of T 1 are thought to be the cause of the anomalous conductivity behaviour.