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A study of the influence of short‐range order, clustering and crystal lattice defects on positron annihilation in α and α + β brass
Author(s) -
Dlubek G.,
Brümmer O.
Publication year - 1978
Publication title -
kristall und technik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0023-4753
DOI - 10.1002/crat.19780130520
Subject(s) - brass , materials science , annealing (glass) , recrystallization (geology) , stacking fault energy , alloy , lattice (music) , cluster analysis , atom (system on chip) , positron annihilation , short range order , crystallography , condensed matter physics , positron , copper , metallurgy , chemistry , physics , electron , nuclear physics , paleontology , computer science , acoustics , biology , embedded system , machine learning
A theoretical model is proposed allowing the consideration of the influence of local neighbourhood of an atom on the positron density enhancement at one or another type of atom in a binary alloy. With the help of this model the direction of the change of angular correlation peak height caused by appearance of short range order or clustering can be predicted. Cu–Zn‐alloys containing 5.4, 15, and 37 weight % Zn are investigated. The peak height of samples quenched from 300°C. show a weak minimum at 90°C. This seems not to be caused by the increase of short‐range order but rather by a process of clustering. probably by segregation of Zn atoms at stacking faults and dislocations. The observed recovery of plastically deformed brass can be well explained by annealing out of vacancies and following recrystallization, where the α + β brass shows characteristic deformation induced properties. Peak height measurements of recovery of crystal lattice defects in binary alloys seems to be only weakly influenced by effects such as short‐range order or tendency of clustering. The formation energy of monovacancies in Cu‐37 wt% Zn is determined to be (0.81 ± 0.02) eV.