Effect of heat treatment on microstructure and mechanical properties of Tantalum plates

Of tantalum and tantalum alloy with high melting point, good conductive thermal conductivity, high chemical stability, excellent high temperature strength, good processability, weldability and low plastic brittle transition temperature, dynamic mechanical properties and excellent after oxidation treatment surface density, stable, high dielectric constant of the amorphous characteristics of oxide film is widely used in electronic, chemical, aerospace, military weapons, medical and health care and other fields, is known as a rising star of the "metal kingdom". Tantalum metal is mainly used in the electronic industry. Tantalum capacitors are small in size, large in capacity, high in reliability, long in life, good in voltage resistance and stable in function. It is widely used in communication, computer integrated circuit, automobile electronic control system, digital electrical appliances and other aspects.

The shell of the whole tantalum capacitor is a deep drawn cup protruding part. The tantalum plate produced in China is prone to cracking, wrinkling, orange peel, ear making and other phenomena during the deep drawing and stretching of the tantalum shell. The finished product rate is low, which makes it difficult to meet the requirements of high performance and high reliability. Macroscopical working hardening rate is relatively low, the tantalum plate grains are fine and uniform, the anisotropy is not obvious, and the mechanical properties are excellent. In addition, the effect of cold deformation amount and annealing temperature on the recrystallization structure of tantalum plate shows that after the large cold deformation (90%), the grains can be refined by appropriate high temperature short time annealing (holding temperature at 850 ℃ for 40 min).However, the effects of cold deformation and heat treatment on mechanical properties of tantalum plate are not studied.

The effects of heat treatment on the recrystallization structure and mechanical properties of pure tantalum were analyzed by means of mechanical properties test, metallographic microscope and scanning electron microscope. The results show that the grain size refinement effect is not obvious after annealing treatment at 900 ℃ for 15, 30 and 45 minutes for 1 mm thick with 10% predeformation and 1.6 mm thick with 20% predeformation. The hardness and tensile strength were increased and the elongation was decreased by predeformation and annealing treatment. With the extension of holding time, the tensile strength and yield strength of 1mm thick samples gradually increased, while the tensile strength of 1.6mm thick samples first decreased and then increased, and the elongation decreased in turn. The analysis of fracture morphology is consistent with the results of mechanical properties.