Study On Preparation,Microstructure And Properties Of High-solid Solution Copper-tin Alloy

Nb3Sn superconducting materials are widely used in high-field strength magnets with a field strength of above 10T due to their superior high field strength properties.At present,multi-core Nb3Sn/Cu superconducting wires are prepared using Cu-Sn alloys as the Sn source by the internal tin method,bronze method and other methods.Nb3Sn strands are imported from Germany(Wieland Group)and other countries,and the ultra-high solid-solubility Cu-Sn alloy is difficult to purchase due to technical blockade in China.In this work,Powder Metallurgy technology was used to fabricate ultra-high Sn content Cu-Sn alloy,and then densified and homogenized by deformation such as rolling and hot extrusion.Cu-Sn alloy with fine grains and ultra-high solid solubility was obtained.Cu-Sn alloys with fine grain and high solid solubility have better performance than the imported Cu-12.5Sn alloy.Based on the above research,the main conclusions are as follows:(1)The grain size of copper-tin alloys prepared by powder metallurgy are about 50μm.Some Sn-rich phases are still segregated at the grain boundaries.(2)Cu-14Sn-0.3Ti alloys prepared with different sintering temperatures have different phase compositions.Within the sintering temperature range of 750 and 800℃,rich α-phase in copper-tin alloy can be prepared.At the sintering temperature of 750℃,the content of solute atoms in Cu-xSn-0.3Ti(x=13,14,15,16,wt.%)alloys with different Sn contents improves with the increase of Sn content improve.At 14wt.%Sn content,when the sintering temperature is 750℃,800℃or 850℃,the density,hardness and electrical conductivity of the copper-tin alloy increase with the increase of the sintering temperature.(3)Rolling,hot extrusion deformation combined with electric pulse treatment can refine the copper-tin alloy grains,make the alloy densfied and uniformed,and introduce a large number of twins and a small amount of dislocations,which is conducive to the improvement of alloy plasticity.In addition,the density,hardness,and electrical conductivity of the copper-tin alloy are significantly improved.(4)When the deformation is 50%and the electric pulse parameter is 50V-400HZ-2min,the copper-tin alloy has fine grains and a relatively uniform structure,and only a small part of the Sn-rich phase segregates at the grain boundary.Cu-14Sn-03Ti alloy with a relatively uniform structure,fine grains,and a large number of twins and stacking faults is obtained.(5)When the hot extrusion temperature is 680℃ and the holding time is 1.5h,a copper-tin alloy with a single α-phase solid solution structure is obtained.In addition,under the same electrical pulse processing parameters(50V,400Hz),when the alloys is processed for 2 minutes,copper-tin alloy with a more uniform structure and refined grains(about 10μm)as well as high toughness can be obtained.