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Competitive nucleation and growth of (Ge) and CuAl 2 phases subjected to different solidification conditions
Author(s) -
Ruan Y.,
Wang X. J.
Publication year - 2015
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201451346
Subject(s) - supercooling , nucleation , materials science , eutectic system , alloy , microstructure , ternary operation , phase (matter) , thermodynamics , crystallography , metallurgy , chemistry , physics , organic chemistry , computer science , programming language
We adapted DSC and drop tube processing techniques to investigate the solidification behavior of (Ge) and CuAl 2 phases in the Al–Cu–Ge ternary alloy comparatively. For the DSC sample only undercooled to 32 K with a low cooling rate, (Ge) phase is the leading nucleating phase and then CuAl 2 phase nucleates. Primary (Ge) block, (Ge+CuAl 2 ) and (Ge+Al) pseudobinary eutectics coexist in the microstructure. In the drop tube, the more competitive nucleation and growth of (Ge) and CuAl 2 phases are caused primarily by high cooling rate and then secondly by large undercooling. On condition that undercooling and cooling rate exceed critical values, simultaneous nucleation of (Ge) and CuAl 2 phases from the alloy melt and subsequently their independent growth contribute to the formation of anomalous (Ge+CuAl 2 ) pseudobinary eutectic grain. Under such condition, a small amount of ternary eutectic grain forms due to the late exclusion of Al solute.