ECAP对Mg-9Al-1.5Bi-0.5In合金组织及电化学性能的影响

Effect of ECAP on microstructure and electrochemical properties of Mg-9Al-1.5Bi-0.5In alloy

镁合金因放电稳定、成本低、标准电位较负非常适合作为电池阳极材料,而目前常用的正挤压态阳极镁合金往往会由于晶粒尺寸差异大、第二相分布不均匀而导致较差的放电性能。为提高挤压态合金的放电性能,采用等通道挤压(ECAP)技术对挤压态Mg-9Al-1.5Bi-0.5In合金进行变形处理,并对其进行组织观察及电化学测试。研究结果表明:ECAP后合金发生了完全动态再结晶,晶粒细化,第二相分布均匀;随着ECAP道次的增加,晶粒尺寸、第二相尺寸均先减小后增大,而第二相的体积分数先增大后减小,在2道次时达到最值;此外,2道次合金具有较好的电化学活性,腐蚀电流密度和腐蚀电位分别为126.63μA/cm^(2)、−1.48713 V,在较小电流密度下,2道次合金具有最大的利用率(53.74%)、功率密度(43.181 mW/cm^(2))和比容量(1412.574 mA·h/g)。因此,在小电流状态下,ECAP 2道次的Mg-9Al-1.5Bi-0.5In合金具有广阔的应用前景。

Magnesium alloy is suitable for anode material of battery due to stable discharge,low cost and negative standard potential.However,the commonly used positive extruded anode magnesium alloy often has poor discharge performance due to large grain size difference and uneven distribution of the second phase.In order to improve the discharge performance of extruded alloy,equal channel corner extrusion(ECAP)technique was used to deform the extruded Mg-9Al-1.5Bi-0.5In alloy,and the microstructure observation and electrochemical test were carried out.The results show that complete dynamic recrystallization occurs after ECAP,the grain size is refined and the second phase is evenly distributed.With the increase of extrusion pass,the grain size and the second phase size both decrease first and then increase,while the volume fraction of the second phase increases first and then decreases,reaching the extreme value when the extrusion pass is 2.The alloy with extrusion pass of 2 has better electrochemical properties,and the corrosion current density and corrosion potential are 126.63μA/cm^(2) and−1.48713 V,respectively.The alloy with extrusion pass of 2 has the highest utilization rate(53.74%),power density(43.181 mW/cm^(2))and specific capacity(1412.574 mA∙h/g).Therefore,Mg-9Al-1.5Bi-0.5In alloy with extrusion pass of 2 is widely used in low current state.