(浙江大学 材料与化学工程学院, 杭州 310027)
摘 要: 通过冷变形拉拔结合中间热处理制备了纤维相增强的Cu-12%Ag(质量分数)合金, 研究了变形过程对组织形态和力学性能的影响。 随着变形程度的增加, 不连续分布的原始共晶体演变成细密的纤维束结构, 合金强度和硬度升高。 在一定变形程度范围内或当共晶纤维束间距约大于150 nm时, 抗拉强度随共晶纤维束间距的变化类似于Hall-Petch关系, 强化效应与位错塞积机制有关; 当拉拔变形超过一定程度或共晶纤维束间距小于约150 nm后, 合金强化速率降低并偏离Hall-Pecth关系, 强化效应可认为与界面障碍机制有关。
关键字: Cu-Ag合金; 纤维组织; 强度; 硬度; 应变率
( College of Materials Science and Chemical Engineering, Zhejiang University, Hangzhou 310027, China)
Abstract: Cu-12%Ag filamentary composite was prepared by cold drawing and intermediate heat treatments. The evolution of filamentary microstructure and mechanical properties were investigated for the alloy at different draw ratio. With the increasing draw ratio, the as-cast eutectic colonies with a discontinuous distribution develop into fine fibrous bundles to result in the increase of the strength and hardness. As the draw ratio is in a certain strain range or the spacing of eutectic fibrous bundles greater than is 150 nm, the ultimate tensile strength dependent on the spacing of eutectic fibrous bundles is similar to the Hall-Petch relationship. The mechanism of pile-up of dislocation can be suggested to be responsible for the strengthening benefit. As the draw ratio is over a certain degree or the spacing of eutectic fibrous bundles is less than 150 nm, the strength increase becomes slow and deviates from the Hall-Petch relationship. The mechanism of athermal obstacles at the interfaces can be suggested to be responsible for the strengthening benefit.
Key words: Cu-Ag alloy; filamentary microstructure; strength; hardness; draw ratio