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Grain‐boundary relaxation peak correlated to the precipitation in Cu–20.4Al–8.7Mn shape‐memory alloy
Author(s) -
Hao Gangling,
Xu Qiaoping,
Wang Hui,
Wang Weiguo
Publication year - 2013
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201228766
Subject(s) - grain boundary , relaxation (psychology) , materials science , activation energy , precipitation , condensed matter physics , alloy , thermodynamics , chemistry , metallurgy , microstructure , physics , psychology , social psychology , meteorology
The grain‐boundary relaxation as well as corresponding internal friction (IF) mechanism in Cu‐based shape‐memory alloy was investigated taking Cu–20.4Al–8.7Mn (at%) as an example. A relaxational IF peak was found at around 214 °C during the heating process, whereas the peak completely disappears during the subsequence cooling process. The IF peak with the activation energy and pre‐exponential factor of 1.60 eV and 3.8 × 10 −18 , respectively, shifting towards higher temperature as the measuring frequency increased indicates that the peak correlates to a thermal‐activation process. The results obtained revealed that the viscous sliding of the grain boundaries should be the operative mechanism for the appearance of the peak. However, the appearance of the γ 2 precipitate particles formed during the heating process provides a reverse contribution to the peak, leading to the disappearance of the peak due to their pinning effect on the grain boundaries.