Tantalum Wire Annealing Texture And Recrystallization Mechanism

As an unit of tantalum anode, tantalum wire plays an important role in tantalum capacitor. Its microstructures and textures can affect tantalum wire's quality and even capacitor's characteristic. More rigorous requisition will be needed for tantalum wire's quality and low cost with thinning of tantalum wire. So it is necessary to study the stability of tantalum wire production technique. The magnitude and homogenization of recrystallization can directly affect tantalum wire's property for annealing being the main production procedure. So it is of a great significance to research the recrystallization mechanism on improving tantalum wire's quality and getting the best production technology.By the pole figures measured by x-ray diffraction and ODF analysis technique as well as metallography, the textures and microstructures of tantalum with production procedure were investigated. The main results of the present work can be summarized as follows:1) The <110> fiber texture was mainly gathered on the a -fiber during the cold drawing. There were three components of the textures, i.e. {441}<110>> {001}<110>> {110}<110>, and strong <111> texture was reserved in the rolling process of repairing tantalum wire. The <110> and <100> fiber textures were strengthened with area reduction of the cold drawing.2) The <110> and <111> fiber textures were be reserved after annealing at different temperatures and approximately decreased with increase of temperature.3) The developments of the texture and microstructure were observed in the tantalum wire with silicon additives, respectively, annealed at 1360癈 and 1500癈 temperatures. It was found that silicon hampered the recrystallization of tantalum wire at 1360癈, and promoted the recrystallizaion of tantalum wire at 1500 癈.4) A model of the development of recrystallization textures in body centered cubic metals proposed by D.N. Lee was applied to explain the 27? -<110> relationship from drawing textures to the primary recrystalliztion textures during annealing and as well from the primary recrystallizaion textures to the second recrystallizaion textures. A corresponding simulation about the microstructures of grains growth in the annealing of tantalum wires was carried out on Monte Carlo theory, The simulation results showed an identical character to experiment.5) The finished wire-products (tantalum wires a and tantalum wires b) were mainly composed of <110> and <111> fiber textures, and there existed different textures of them for the distinct production requirements.The affects of silicon additives in tantalum wires and the production processes of tantalum wire on the recrystallization textures were investigated in this thesis. The recrystallization model proposed by D.N. Lee can explain the relationship between annealing texture and drawing texture of tantalum wire. And themicrostructure was simulated as well. The annealing texture and recrystallization mechanism of tantalum wire were analyzed in this thesis.