冷拉拔Cu-2.5% Fe-0.2% Cr和Cu-6% Fe合金的显微组织与性能（英文）

Microstructure and properties of cold drawing Cu-2.5% Fe-0.2% Cr and Cu-6% Fe alloys

目的:探索Cu-Fe合金中纳米尺寸和微米尺寸的Fe相的变形行为及区别。方法:1.通过热处理在Cu-2.5%Fe-0.2%Cr合金中得到纳米级的Fe析出相,在Cu-6%Fe中得到微米级的Fe析出相;2.通过冷拉拔手段使铜合金从棒状逐步变形成线材;3.使用光学显微镜、扫描电镜和透射电镜观察微观组织,并用万能电子试验机测量抗拉强度,用标准四点法测量电阻率。结论:1.通过热处理在Cu-6%Fe合金中得到尺寸约50 nm的初生Fe颗粒,在Cu-2.5%Fe-0.2%Cr合金中得到尺寸约50 nm的次生Fe颗粒;2.初生Fe颗粒在冷拉拔过程中转变成丝带状纤维,Cu/Fe相界面密度随变形量增加而增加,从而使Cu-6%Fe合金的强度和电阻率都随之增大;3.次生Fe颗粒即使在η=6的时候也难以变形,保持着球形的形貌,同时高密度的位错环绕着Fe颗粒;Cu-2.5%Fe-0.2%Cr合金的强度随变形量增加而增大,遵循Orowan强化机制;Cu-2.5%Fe-0.2%Cr合金的电阻率几乎保持不变,因为Cu/Fe相界面密度在冷拉拔过程中几乎不变;4.尺寸效应和Fe析出颗粒与Cu基体的非共格界面对Fe析出颗粒在冷拉拔过程中不变形起到重要作用。

High strength and high conductivity Cu-based materials are key requirements in high-speed railway and high-field magnet systems. Cu-Fe alloys represent one of the most promising candidates due to the cheapness of Fe compared to Cu-Ag and Cu-Nb alloys. The high strength of Cu-Fe alloys primarily relies on the high density of the Cu/Fe phase interface, which is controlled by the co-deformation of the Cu matrix and Fe phase. In this study, our main attention was focused on the defor- mation behavior of the Fe phase using different scales. Cu-2.5% Fe-0.2% Cr （in weight） and Cu-6% Fe alloys were cast, an- nealed, and cold drawn into wires to investigate their microstructure and properties evolution. Cu-6% Fe contains Cu matrix and Fe, which become the primary particles in the micrometer scale after solution treatment. Cu-2.5% Fe-0.2% Cr contains Cu ma- trix and Fe precipitate particles in a nanometer scale after solution and aging treatment. The Fe primary particles were elongated and evolved into ribbons in a nanometer scale while the Fe precipitate particles were hardly deformed even at a drawing strain of 6. The reason for the unchanging characteristics of Fe precipitate particles is due to the size effect and incoherent phase interface of Cu matrix and Fe precipitate particles. The strength of both Cu-6% Fe and Cu-2.5% Fe-0.2% Cr alloys increases with the increase in the drawing strain. The electrical resistivity of Cu-6% Fe gradually increases and that of Cu-2.5% Fe-0.2% Cr keeps almost constant with the increase in the drawing strain.