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On the influence of impurity additions and quenching temperature on the course of the microhardness (HV) during a two‐step ageing treatment of an Al‐2.0 at.%Zn‐1.3 at.%Mg Alloy
Author(s) -
Gerlach R.,
Löffler H.
Publication year - 1983
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.2170180312
Subject(s) - impurity , quenching (fluorescence) , nucleation , ageing , alloy , homogeneous , two step , indentation hardness , materials science , analytical chemistry (journal) , chemistry , metallurgy , thermodynamics , microstructure , physics , chromatography , fluorescence , genetics , organic chemistry , quantum mechanics , biology , combinatorial chemistry
A pure as well as the analogous technical alloy were directly quenched from T q = 400 °C or 490 °C to T a , preaged at T a (ranging between 50 °C and 160 °C) various times ( t a ), and subsequently postaged at R.T. up to t post = 42 d. — Ageing the samples below the upper limit temperature of the homogeneous formation of G.P. zones ( T hn ) no essential difference in the course of the HV‐number attained after one‐ as well as two‐step ageing in dependence on the addition of impurity atoms and T q could be found. — Contrary to this behaviour after pre‐ageing at T a > T hn and postageing at R.T. a variation of both T q and the content of impurity atoms shows a considerable effect. The reason is the difference in the density of nucleation sites for heterogeneous formation of precipitates of the η′‐ and/or η‐phase in dependence of T q and impurity content.