亚微米晶Cu-5%Cr冷拉拔的组织与性能研究

Microstructures and properties of cold drawn submicron crystalline Cu-5wt%Cr material

通过机械合金化、热压制坯和热挤压制备了完全致密的亚微米晶Cu-5%Cr(质量分数,以下同)高强高导电材料,在此基础上研究了亚微米晶Cu-5%Cr冷拉拔所引起的组织与性能的变化。结果表明,冷拉拔使亚微米晶Cu-5%Cr中的位错密度增大,并形成了胞状组织;使晶粒尺寸约400～500nm的亚微米晶Cu-5%Cr的晶粒进一步细化为100～200nm;经过550℃退火后得到了晶粒尺寸为200～300nm的再结晶晶粒。这说明通过大塑性变形和适当的再结晶,亚微米晶Cu-5%Cr的晶粒可以被进一步细化。亚微米晶Cu-5%Cr经过冷拉拔后产生了加工硬化,且随拉拔变形量的增加,其强度和伸长率都提高,而导电率降低,其室温断裂方式为微孔聚集型断裂。这说明其塑性变形机制仍以位错滑移为主;随晶粒的进一步细化,其延性进一步提高。

By mechanical alloying, hot compacting and hot extrusion, fully densified submicron crystalline Cu-5wt% Cr alloy with high strength and high electrical conductivity has been prepared. Variations of properties due to cold drawing of submicron crystalline Cu-5wt% Cr have been investigated. The results show that, by cold drawing, the dislocation density increases and cellular structures are formed. The grainsize of Cu-5wt% Cr alloy is refined from 400-500nm to 100-200nm. When the cold drawn Cu-5wt% Cr is annealed at 550℃, grain size of 200-300nm can be obtained. It demonstrates that the grains of submicron crystalline Cu-5wt% Cr can be further refined through heavy plastic deformation and proper recrystallization. After cold drawing, work -hardening occurs in submicron crystalline Cu-5wt % Cr. With drawing deformation increasing, both the tensile strength and the tensile elongation increase, but the electrical conductivity decreases. The room temperature tensile fracture is caused by the accumulation Of pores. These demonstrate that dislocation glide is still the main mechanism in plastic deformation of submicron crystalline Cu-5wt%Cr. With the grains further refining, the ductility of the Cu-5wt%Cr is further improved.