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On the position of the upper limit temperature of homogeneous nucleation of precipitates in low concentrated AlZn alloys
Author(s) -
Wendrock G.,
Löffler H.,
Raphelt I.,
Truong Chu Thien
Publication year - 1987
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.2170220418
Subject(s) - nucleation , isothermal process , homogeneity (statistics) , homogeneous , thermodynamics , atmospheric temperature range , materials science , chemistry , crystallography , analytical chemistry (journal) , physics , chromatography , statistics , mathematics
The upper limit temperature T hn of the onset of homogeneous nucleation of Guinier‐Preston (GP) zones was determined for three AlZn alloys with x Zn = 4.5, 6.0 and 8.0 at.% by SAXS investigations (cooling from the range of homogeneity to various temperatures T a and ageing at T a ). The results are T hn = (95 ± 3) °C for x Zn = 4.5 at.%, (118 ± 3) °C (6.0 at.%) and (154 ± 3) °C (8.0 at.%), respectively. The obtained results fit well the data known for the alloys with higher contents of Zn. It is stressed that one has to distinguish between T hn , determined by isothermal measurements after a direct quench or cooling to the respective T a , and the upper limit temperature T rhn of the onset of the rapid homogeneous nucleation of GP zones (continuous cooling).