Study On Preparation Process And Microstructure And Properties Of High-conductivity Free-cutting Tellurium Copper Alloy

The highly conductive and free-cutting tellurium copper alloy is a structural and functional integrated material with excellent physical and mechanical properties.It is an excellent material for connectors and contact materials.It has broad prospects for applications in large current connectors such as charging piles.For copper alloys,compared with other strengthening elements,when Te is added to copper,the resistance increase rate of the copper material is low,and when the content is low,the copper material can be strengthened,but its alloy has been applied.The brand is relatively single,and the traditional production methods are also relatively complex,so more indepth research and development are required in modern manufacturing.This paper first studies and analyzes the characteristics of the traditional "threestage" process for producing copper tellurium rods,and studies the effects of different Te contents on the structure,mechanics and electrical conductivity of copper alloys.The results show that the addition of a small amount of tellurium does not greatly affect the mechanical and electrical properties of the copper material.The second phase containing tellurium precipitated during solidification is mainly distributed at the grain boundaries.After hot extrusion,the strength and conductivity of the alloy are significantly improved.The electrical conductivity of the alloy after the drawing process is basically about 94% IACS,and the strength is significantly higher than that of copper with the same deformation.Through the development and optimization of the short-flow process of continuous lead-up + continuous extrusion,a multi-component tellurium copper alloy bar with a Te content of 0.02 to 0.3% was prepared,and a production process for mass production of the alloy was formed the physical and mechanical properties were analyzed.The research shows that the continuous up-drawing process can produce a high-quality tellurium-copper tellurium alloy billet,and then the continuous hotopening of tellurium-copper tellurium alloy can be completed through the continuous extrusion process.After continuous extrusion,the alloy obtains a fine dynamic recrystallization structure.Compared with the casting rod,the distribution of tellurium has been homogenized,and the mechanical and electrical conductivity of the alloy has been significantly improved.The rate has been greatly increased.After drawing deformation,the electrical conductivity of the alloy can reach 92% IACS.Compared with the three-stage process of "iron mold ingot + hot extrusion",the conductivity and mechanical properties of the tellurium copper alloy prepared by the short process "continuous upward drawing + continuous extrusion" are equivalent,and have a slight advantage;in terms of elongation performance The tellurium copper alloy prepared by the short flow process is superior to the traditional process.The Te element exists in the Cu-Te alloy in the form of Cu2 Te in bcc,and the second phase with larger size is severely segregated in the as-cast state,mainly concentrated at the grain boundaries.After continuous extrusion,the particles of the second phase are finer and more uniformly distributed;the second phase of cold drawing is elongated in a chain or band shape with the drawing direction.The cutting performance of the researched and developed copper tellurium alloy is significantly better than that of copper.With the increase of Te content,the cutting performance gradually improves.The cutting performance of the tellurium copper alloy differs in different processes,and the best in the drawn state.After continuous extrusion and drawing,the alloys with the content of 0.02% Te,0.07% Te and 0.10% Te are annealed.Studies have shown that annealing at 400 ℃ for 1h has excellent overall performance.When annealed at 350 ~ 390 ℃ for 1h,the change in tensile strength is very small,and the alloy is in the recovery stage.After annealing at 400 ℃ for 1h,the tensile strength drops significantly,and the alloy begins to enter the recrystallization stage.Cu-Te alloy fracture belongs to toughness Fracture,as the annealing temperature increases,the size of the dimple becomes larger and deeper,and the shape becomes more rounded.In this paper,a large-scale industrial test of continuous introduction and continuous extrusion of a multi-component tellurium copper alloy was realized.The related products were successfully used in high-power charging piles.Industrial tests and applications show that the new technology developed has realized disc production,which has the advantages of high yield,high production efficiency,and low energy consumption.At the same time,the product has high hardness,high conductivity,and the machining speed has increased by three times.Products and technologies have broad application prospects.