摘要
Cu-12% Fe （in weight） composite was prepared by casting, pretreating, and cold drawing. The microstructure was observed and Vickers hardness was measured for the composite at various drawing strains. Cu and Fe grains could evolve into aligned filaments during the drawing process. X-ray diffraction （XRD） was used to analyze the orientation evolution during the drawing process. The axial direction of the filamentary structure has different preferred orientations from the radial directions. The strain of Fe grains linearly increases with an increase in the drawing strain up to 6.0, and deviates from the linear relation when the drawing strain is higher than 6.0. With an increase in the drawing strain, the microstructure scales of Fe filaments exponentially decrease. The density of the interface between Cu and Fe phases exponentially increases with an increase in the aspect ratio of Fe filaments. There is a similar Hall-Perch relationship between the hardness and Fe filament spacing. The refined microstructure from drawing deformation at drawing strains lower than 3.0 can induce a more significant hardening effect than that at drawing strains higher than 3.0.
研究目的:阐明铜铁合金在拉拔变形过程中,微观组织和硬度的变化规律。创新要点:1.考察铜铁合金变形过程中,铜基体和铁枝晶组织的变化特点;2.研究铁纤维的尺寸及Cu/Fe相界面密度与合金变形量的关系;3.探讨了铁纤维与硬度关系符合Hall-Petch关系的匹配程度。研究方法:1.通过固溶时效处理使得铁枝晶均匀地分布在铜基体中;2.通过冷拉拔手段使得铜合金从棒状逐步变形成线材;3.使用扫描电镜观察微观组织,并使用维氏硬度仪测试样品硬度。重要结论:1.铁枝晶在合金变形过程中逐渐变成铁纤维。随着冷变形进行,线材纵截面的铜纤维形成(110)择优取向,铁纤维形成(100)择优取向;在横截面上的铜纤维形成(111)择优取向,铁纤维形成(110)择优取向;2.铁纤维的厚度、宽度和间距随变形量的增加呈指数降低,Cu/Fe相界面密度随铁纤维宽厚比的增加而呈指数增加。在变形量小于6.0时,铁相的应变随变形量线性增加,当变形量大于6.0时,铁相的应变偏离这种关系;3.铁纤维的间距和合金硬度存在Hall-Petch关系。当变形量小于3.0时,纤维组织细化对硬度带来的影响较为明显。
基金
Project supported by the National Natural Science Foundation of China （Nos. 11202183 and 50671092）, the National Science ＆ Tech- nology Pillar Program during the Eleventh Five-Year Plan Period （No. 2009BAG12A09）, the National High Technology Research and Development Program （863） of China （No. 2011AAllA101）, and the Zhejiang Provincial Natural Science Foundation of China （No. Y4100193）
