Investigation Of The Microstructure And Mechanical Properties Of QA17 Copper Alloy Based On Deformation

With the rapid development of semiconductor integrated circuit micro processing technology and ultraprecision machining technology,MEMS has integrated electronic technology and mechanical characteristics,becoming one of hot research fields in science and military.MEMS integrates micro mechanical elements and electronic circuits on the same chip,and micro plane springs used for micro sensors play the role of transmission of force,displacement and energy.Aluminum bronze,as an ideal material for micro spring,has good mechanical properties and fatigue resistance and can be improved by heat treatment and deformation modification.This paper,based on QA17 high strength copper alloy,investigated the microstructure and mechanical properties in different solid solution treatment and rolling at room temperature,researched the influence of the size effect,on the purpose of providing the sufficient theoretical basis of planar micro spring forming of high fatigue performance.The main conclusions of this paper are as follows:The best solution treatment process for QA17 copper alloy is 850℃+5h.In this process,the elongation at length was 85%higher than that of the cast,and the plasticity was improved obviously,with the excellent coordination of plastic and strength.The phase composition of the alloy changed from α+κ+γ2 to α+β’+κ after solid solution treatment.The percentage of a phase has the largest contribution to elongation and plasticity of alloy.The ratio of β phase is the more important factor of the tensile strength and yield strength,while the ratio of κ phase is significant to the hardness.For example,When the temperature is 850℃-5h,the proportion of the a phase reaches the maximum value of 65.36%,and the elongation is Amax=21.4%at the maximum.When the temperature is 950-5h,the content of theβ phase is up to 54.24%,and the hardness is 89.2HRB reaching a maximum.Therefore,to improve the cold deformation capacity of the alloy,we should start with the increase of the proportion of the phase of the a phase.Fiber texture,which can be easily gained by rolling,will greatly improve the life of machine parts.In the cold rolling process of aluminum bronze,When the deformation increases,the grain becomes more slender,with a phase extending along the rolling direction and presenting the shape of fiber distribution.By rolling,the typical plate texture of the copper alloy and the obvious preferred distribution is observed.The larger rolling reduction is,the higher degree of texture optimization is.Correspondingly hardening index is approximately up to 0.28,which is 2.3 times as cast and the deformation ability is weaken.Therefore,the suitable rolling deformation should be chosen in the plane micro spring forming,which can not only improve the properties of the parts,but also facilitate the forming of the parts.The size effect of aluminum bronze in the tensile test is found.The grain size and thickness of the sample will affect the strength and elongation of the material.The strength is especially sensitive to the change of thickness.With the thickness decreasing,the yield strength and tensile strength of aluminum bronze increase,while the elongation decreases.The thicker the sample is,the greater the magnitude of strength change is.Size effect related to the processing technology and the performance of the workpiece must be taken into considered in the process of micro forming of aluminum bronze.