Signs of the presence of an ordered phase in the Cu-5.9 at.% Pd alloy after its long-term annealing at a moderate temperature

О.С. Новикова ORCID logo , А.Е. Костина ORCID logo , Е.Г. Волкова, Ю.А. Саламатов, А.В. Глухов, А.Ю. Волков, В.В. Марченков, В.С. Гавико, Ю.М. Устюгов показать трудоустройства и электронную почту
Получена 10 июля 2022; Принята 20 сентября 2022;
Эта работа написана на английском языке
Цитирование: О.С. Новикова, А.Е. Костина, Е.Г. Волкова, Ю.А. Саламатов, А.В. Глухов, А.Ю. Волков, В.В. Марченков, В.С. Гавико, Ю.М. Устюгов. Signs of the presence of an ordered phase in the Cu-5.9 at.% Pd alloy after its long-term annealing at a moderate temperature. Письма о материалах. 2023. Т.13. №1. С.3-8
BibTex   https://doi.org/10.22226/2410-3535-2023-1-3-8
We observed the ordered phase particle experimentally by the TEM method. The temperature of the order–disorder phase transition in the Cu-5.9Pd alloy was estimated as Tc ≈ 340°С.The structure and electrical properties of the Cu-5.9 at.% Pd alloy were studied after its annealing for two months at 250°C. As a result of such a long-term thermal treatment, in the XRD patterns taken from the alloy one can observe a weak superstructural (100) reflection, which seems abnormal, since the alloy can only be in the state of a disordered single-phase solid solution (as it follows from the generally accepted Cu-Pd phase diagram). Quantitative analysis of the X-ray diffraction patterns reveals the presence of two new phases with different contents of Pd. An assumption is made that L12 superstructure can be formed in the Pd-enriched phase. The specific features observed in the temperature dependence of electrical resistivity, as well as the TEM results, confirm this set-forth hypothesis of ours. Using the resistometric method, the temperature of the order-disorder phase transition in the alloy was estimated as Tc ≈ 340°С. It is concluded that the position of the A1-(A1 + L12) phase boundary in the Cu-Pd phase diagram requires more precise definition in the region of compositions on the side of the low Pd content.