Dissertation
Dissertation > Industrial Technology > General industrial technology > Materials science and engineering > Composite materials > Metal composite materials

The Relationship between Structuer and Properties with the Deformation Thchnics of Submicron Grains Cu-5Cr Composite Material

Author ChenZuo
Tutor GengYaoHong;HeWenXiong
School Harbin Institute of Technology
Course Materials Processing Engineering
Keywords Cu-5Cr composite material hot extrusion drawing submicron crystalline
CLC TB331
Type Master's thesis
Year 2006
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Cu-Cr mutual insolubility metal composites have been widely used for integrated circuit lead frames, heavy-duty electrical contacts and electrical wiring owing to their high strength and hardness, good electrical and thermal conductivity. It has been proved that Cu-Cr composite powders with fine microstructure can be prepared by mechanical milling,the Cu-Cr compact composites with submicron grains can be obtained by pressureless sintering and Hot Hydrostatic Extrusion(HHE). However, little research has been done on the deformation mechanism in the process of plasticity working. In this paper, further deformation has been carried out in order to investigate the relationship between its structure and properties with the deformation technics based on the compact Cu-5Cr composite material with submicron grains prepared by mechanical alloying and solid state sintering. And obtained the new Cu-5Cr composite material with finer microstructure and better mechanical properties by further deformation processing. Research on the following aspects has been accomplished in this dissertation.The compact Cu-5Cr billets with submicron grains have been respectively twice hot extruded, reducing the billets from 16mm to 2mm in diameter. The hot Extrusion technics has been confirmed after the observation of microstructure and testing of mechanical properties, the effects of extrusion temperature and deformation extent on the microstructure and properties have also been discussed. In the process of hot extruding, the processes of work induration and dynamic softening were occurring at the same time. It has been proved that the dynamic softening mechanism is dynamic recovery and dynamic recrystallization. The Cu-Cr composite material is getting softer as the extrusion temperature is raised, that is, the strength and hardness are step down while plasticity improved. The hot extrusion with larger deformation extent can obtain finer microstructure. The process of hot extrusion is thought to increase the rectangular distribution of Cr granules in Cu matrix and the deposition of Cr particles, which can successfully inhibit the growth of grains, as a result, the mechanics properties and electrical conductivity are both increasing. Further study showed that the strengthening of

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