柱状晶组织Cu-Ni-Si合金的形变时效组织调控及强化机理研究

Cu-Ni-Si合金由于具有较高的强度、导电性、导热性及良好的加工性能，已成为制备引线框架的一种重要材料。目前Cu-Ni-Si合金带材的传统制备加工工艺存在合金铸坯组织不均匀、晶粒取向杂乱，加工硬化率大，中间退火次数多，时效析出不充分、析出相尺寸较单一、弥散分布不够且容易长大和综合性能低等一系列问题。针对上述问题，本项目采用定向凝固技术制备C70250铜合金带坯，对柱状晶组织C70250铜合金带坯直接进行三种形变热处理，省略均匀化退火和固溶处理工序，研究直接时效、单次冷轧时效工艺和反复冷轧时效工艺对柱状晶组织C70250铜合金带材晶粒结构、位错及析出相的影响，揭示柱状晶组织C70250铜合金形变时效过程中的塑性变形机制、析出行为和相互作用机理，建立柱状晶结构和析出相对C70250铜合金强度和导电率的协同提升理论，为实现高强高导Cu-Ni-Si合金带材的短流程制备提供理论依据。

Cu-Ni-Si alloy has become an important material for lead frame due to its high strength, conductivity, thermal conductivity and good processability. At present, the traditional preparation process of Cu-Ni-Si alloy strip has a series of problems, such as uneven structure, disordered grain orientation, high work hardening rate, many times of intermediate annealing, insufficient aging precipitation, single precipitation size, insufficient dispersion distribution, easy growth and low comprehensive properties. In this project, C70250 copper alloy strip billet with columnar structure is prepared by directional solidification technology. Three kinds of thermomechanical treatment were directly carried out on the columnar structure strip. The homogenization annealing and solution treatment processes are omitted. The effects of direct aging, single cold rolling-aging and repeated cold rolling-aging on the grain structure, dislocation and precipitate phase of columnar structure C70250 copper alloy strip are studied. The plastic deformation mechanism, precipitation behavior and interaction mechanism of columnar structure C70250 copper alloy during deformation aging are revealed. The theory of synergistic enhancement of the strength and electrical conductivity of columnar grain structure and precipitation of C70250 copper alloy is established, which provides a theoretical basis for realizing the short process preparation of high strength and high electrical conductivity Cu-Ni-Si alloy strip.