The Electric Field Aging On The Microstructure And Properties Of 2e12 Aluminum Alloy

The influence of electric field ageing on the properties and microstructures of 2E12 aluminum alloy had been investigated, including the effect of the electric field on the tensile strength,fatigue property,electric conducticity and the hardness of the alloy.The study was proceeded by means of tensile tests,hardness tests,fitigue life test, fatigue crack propagation tests,electric conductivity tests transmission electron microscopy(TEM) and scanning electron microscopy(SEM). The main conclusions are as follows:(1) The influence of electric field ageing on the mechanical properties and microstructures of 2E12 aluminum alloy had been investigated and the mechanism of the effect of an electric field was analyzed.The results show that the S' phase(Al₂CuMg) particles and T phase(Al₂₀Cu₂Mn₃)particles were smaller after 16kV/cm electric field aging,which decreased the yield strength of the alloy.Meanwhile the grain boundaries of the specimen aged under an electric field were composed by numerous ultra micro precipitates,the ductility of the alloy was improved.The mechanism analyses showed that the electric field can accelerate the nucleation of the new phase S',while the coarsening of the S' is retarded by the electric field during the aging process.The electric field can influence the potential field of vacancies.As a result,the vacancies tend to move toward the opposite direction of the electric field.(2)The influence of electric field aging on the fatigue properties and microstructures of 2E12 aluminum alloy had been investigated.The fatigue life of the 2E12 aluminum was improved and the fatigue crack propagation speed was decreased by an electric field ageing.The SEM analyses of the fatigue crack propagation tests samples showed that the fatigue strip width of the samples aged with an electric field of 16kV/cm is smaller than those aged without an electric field,especially in the middle and final phase of the fatigue steady propagation zone.(3) The influence of an electric field on the aging hardening curve and electric conductivity of 2E12 aluminum alloy had been investigated. The analyses of aging hardening curve showed that the electric field of 16 kV/cm can reduce the time for the 2E12 alloy to reach the aging hardness peak,however,the peak of the hardness was decreased.The electric conductivity curve of the samples aged with an electric field of 16kV/cm is lowered than those aged in normal conditon,that means the electric field applied during the ageing process decreased the electric conducticity of the 2E12 alloy.