Study On Aging Microstructure And Performance Of Cu-Ti Alloy Produced By Surface Mechanical Attrition Treatment

Cu-Ti alloys have attracted attention and applications in the related electrical and electronic fields because of their high strength,high elasticity,and high electrical conductivity.Cu-Ti alloy aging-strengthening alloys have phase transformation characteristics such as spinodal decomposition and ordering during aging treatment.Different alloy compositions,processing techniques,and time-efficient processing systems all affect the total phase transition characteristics and performance of copper and titanium.Surface mechanical attrition treatment is commonly used in recent years to improve the performance of metallic materials and can prepare nanocrystalline surface layers on the surface of materials.Aging treatment promotes the precipitation of solid solute atoms and enhances the overall mechanical properties of the material.This article chooses Cu-4wt%Ti alloy to adopt SMAT+ aging treatment and aging treatment separately,and combines surface mechanical attrition treatment(SMAT)with aging treatment to study the SMAT of Cu-4wt%Ti alloy.The effect of the comparison between the SMAT-treated and non-SMAT-treated Cu-4wt% Ti alloys was investigated.The effects of different aging temperatures and different aging times on the aging process were also studied.To explore the effect of surface mechanical grinding on the aging process of Cu-4wt% Ti alloys.The main results of the experiment are as follows:(1)The nanocrystalline layer was successfully prepared on the surface of the Cu-4wt% Ti alloy after the Cu-4wt% Ti alloy was solution treated at 1203 K for 120 min and then treated with SMAT for 60 min.The thickness of the nanocrystalline layer was approximately 30 μm.There are a large number of deformation twins in the microstructure.(2)The aging of SMAT treatment can significantly increase the hardness of the material.With the increase of aging time,the hardness shows a trend of increasing first and then decreasing.The hardness reaches a peak at 8 hours aging treatment,and at the same aging time,at a distance of 40 μm from the surface layer.The peak hardness at this ageing temperature is reached.When aged at 200°C for 8 h,the peak hardness at a distance of 40 μm from the surface increased by 68.6% with respect to the substrate.At an aging treatment at 500°C for 8 h,the peak hardness at a distance of 40 μm from the surface increased by 77.1% with respect to the substrate,and the hardness increased at an aging treatment at 500°C.Significantly higher than at 200 °C;non-SMAT specimens increased hardness after aging time,peaking at 4 h aging.Aging after SMAT can greatly increase the material hardness.(3)After the aging of SMAT,the microstructure was changed obviously.With the increase of aging time,the degree of twinning increased and the etching deepened.The aging of the microstructure after SMAT is mainly near the peak hardness.The closer to the peak position,the larger the volume and number of twins,the twin boundaries significantly increase the strength of the material.The aging treatment at 500°C has a large number of precipitated phases at and near the grain boundaries,and the morphology is mainly acicular.As the time of validity increases,there is a clear tendency for the precipitation phase to grow.(4)The electrical conductivity of Cu-4wt% Ti alloy increases with the aging time,and the aging time is 1h,which is the rapid growth phase of electrical conductivity.After 1 h,the growth rate slows down and reaches a constant value after 12 h.After the SMAT,the conductivity of the aging treatment at 500°C reached 18% IACS,while that without the SMAT 500°C was 12% IACS.The conductivity of the aging treatment after SMAT was significantly higher than that of the non-SMAT aging treatment.The change trend of the electrical conductivity at high temperature aging treatment is similar to the low temperature aging,but the electrical conductivity at high temperature aging is obviously better than the low temperature aging.Therefore,the high temperature is more conducive to aging precipitation,improve the conductivity.Hardness at this point reaches a peak hardness at the time of the 8 h treatment,effectively achieving a combination of strength and electrical conductivity.