Research On The Ageing Behavior Of C19400Alloy Under Influence Of Current And Magnetic Field

In recent years, with the rapid development of electronic information industry, integrated circuit keeps developing in a trend toward high-density, miniaturization and multifunction. As a result, there is an increasing demand for the comprehensive performance of lead frame materials in IC. C19400alloy is a kind of high-strength and high-conductivity copper alloy which has a high development prospects, widely used as the lead frame materials presently. Studying on the solution and ageing behavior of the alloy, together with further searching new preparation and processing techniques, have great significance on the improvement of the properties of strength and electrical conductivity of the alloy.Current and magnetic field are used in the ageing process of C19400alloy in the paper. As-cast structure and Influence of current, magnetic field on aged microstructure of C19400alloy were investigated by optical microscopy, SEM, XRD and TEM. Meanwhile, explore the performance of current and magnetic field on improving the properties of C19400alloy through the conductivity and tensile strength testing. The main research conclusions are as follows:1. As-cast microstructure of C19400alloy is made up of a-Cu and Fe2P phase. a-Cu phase is equiaxed grain, and Fe2P phase is distributed in the grain boundary.2. The precipitates of C19400alloy during regular ageing are Fe phase and Fe2P phase. When C19400alloy is aged under pulsed current or magnetic field, the size of precipitates decreases, the number increases but the kinds of the precipitates have no change.3. Pulse current promotes the ageing process. Alloy conductivity is increased with the increasing of pulse current continuously ageing time and temperature, tensile strength after the peak has fallen slightly when C19400alloys ageing with pulse current. The conductivity of the alloy gradually increases with the increase of current intensity, and the tensile strength first increases but it has a downward trend after the peak. The tensile strength of the alloy is453.7MPa, the corresponding conductivity is55.6%IACS When frequency of pulse current is500Hz, current intensity is300A/cm2, ageing parameter is 450℃×4h.4. The conductivity and tensile strength of C19400alloy can be further increased when the alloy aged under the act of both cold deformation and pulse current.The tensile strength of the alloy reaches the peak value584MPa and the corresponding conductivity is61.5%IACS when cold deformation is70%, current frequency is500Hz, current intensity is300A/cm2, ageing parameter is450℃×4h5. Strong magnetic field promotes the ageing process. Alloy conductivity is increased with the increasing of strong magnetic continuously ageing time and temperature, tensile strength after the peak has fallen slightly when C19400alloys ageing with strong magnetic field. The tensile strength of the alloy is480MPa and the corresponding conductivity is61%IACS When magnetic field intensity is12T, ageing parameter is450℃×4h.6. The second phase of C19400alloy can be rapid precipitated and the conductivity and tensile strength are significantly improved when the alloy aged under the act of both cold deformation and strong magnetic. The tensile strength of the alloy reaches the peak value590MPa and the corresponding conductivity is63.4%IACS When cold deformation is70%, magnetic field intensity is12T and ageing parameter is450℃×4h.