摘要
以混合盐法制备不同TiB_(2)颗粒含量的TiB_(2)(p)/ZL205复合材料(其中TiB_(2)颗粒含量为2%,4%,6%,质量分数),通过热分析、扫描电镜(SEM)、电位极化测量和电化学阻抗谱测量等方法研究TiB_(2)含量对复合材料组织和耐蚀性的影响。结果表明:随着TiB_(2)颗粒含量的增多,复合材料凝固速度变慢,θ相析出量减少且析出温度由547.71℃降低到531.87℃。在铸态下,随着TiB_(2)颗粒含量增加,团聚物的数量和尺寸变大,晶间腐蚀和点蚀数量增加,自腐蚀电流密度(icorr)值提高,对电化学阻抗谱进行拟合,发现钝化膜电阻(Rf)以及电荷转移电阻(Rct)之和(Rf+Rct)逐渐减小,复合材料耐蚀性逐渐降低;经T6热处理后,复合材料中析出相的数量明显减少,且分布变得更加弥散,且随着TiB_(2)颗粒含量的增加,大尺寸颗粒团聚物内部变得更加弥散,复合材料耐蚀性逐渐降低。相比于相同颗粒含量铸态下的试样,T6热处理后晶间腐蚀和点蚀的数量相对减少,icorr值提高但幅度较小,(Rf+Rct)值明显提高,说明经T6热处理后复合材料耐蚀性有所提高。
Particle-reinforced aluminum-based composite materials were gradually used in various major fields due to their high specific strength,high specific stiffness,low thermal expansion coefficient,and good thermal stability.While particle reinforcement improved the mechanical properties of aluminum alloys,people often ignored the impact of particles and their segregation on the corrosion resistance of aluminum alloys.Thermal analysis combined with scanning electron microscopy(SEM)and electrochemical measurements were used to investigate the effect of TiB_(2)particle content on the solidification process of TiB_(2(p))/ZL205 composites and the corrosion resistance of composites in the as-cast and T6 states.The TiB_(2(p))/ZL205 composite material with different TiB_(2)particle contents prepared by mixed salt method(TiB_(2)content of 2%,4%,6%,mass fraction).Remelting was performed in a resistance furnace at 750℃.for 1.5 h.The temperature acquisition deviced DAQ-Central was used to record the temperature change data of the composite material during the solidification process,the recording frequency was to collect 100 temperature data points per second,and then used Origin8.5 to fit the collected temperature data.The influence of TiB_(2)particle content on the solidification process of composite materials was studied.Taking half of the samples for T6 heat treatment,and put the as-cast and T6 samples into 3.5%NaCl aqueous solution to soak for 60 d.The morphology of the structure was observed by SEM,and the Zahner-IM6 e electrochemical workstation was used to perform potential polarization measurement,the sweep voltage range was-150~150 mV,the sweep rate was 1 mV·s^(-1).The electrochemical impedance spectroscopy measurement was carried out at the same time,the sweep frequency range was 100 kHz~100 MHz,swept from high frequency to low frequency,the signal amplitude was 10 mV,and Origin8.5 was used to fit the experimental data.The thermal analysis curve showed that the solidification speed of the composite material became slower with the increase of TiB_(2)particle content.In addition,0 phase decreased and the precipitation temperature decreased from 547.71 to 531.87℃.From SEM result,it was found that in the as-cast state,TiB_(2)particles gathered at the grain boundaries to form large-scale agglomerates withθphase,with the particle content increasing,the number and size of agglomerates became larger.Through the observation of the corrosion morphology,it was found that the composite materials often had intergranular corrosion and pitting corrosion,the surface scan confirmed that the existence of copper-poor areas was the main reason for the intergranular corrosion of composite materials.In the ascast state,due to the increase in the particle content,the number and size of agglomerates became larger,the number of intergranular corrosion and pitting corrosion increased.The self-corrosion current density(icorr)increased.By fitting the electrochemical impedance spectrum,it was found that the sum of the passivation film resistance(Rf)and the charge transfer resistance(Rct)gradually decreased,the corrosion resistance gradually deteriorated.After T6 heat treatment,the number of precipitated phases in the composite material was significantly reduced,and the distribution became more dispersed.As the content of TiB_(2)particles increased,the interior of the large-sized particle aggglomerates became more dispersed.The corrosion resistance of the composite material gradually decreased.However,compared with the sample with the same particle content in the as-cast condition,the number of intergranular corrosion and pitting corrosion after T6 heat treatment was relatively reduced.The icorr value was increased but the amplitude was small,and the(Rf+Rct)value was obviously improved,which showed that the corrosion resistance of the composite material was improved after T6 heat treatment.This article used thermal analysis and SEM to combine the effects of TiB_(2)particles on the morphology of theθphase in the composite material and the solidification temperature.Through the research on the corrosion resistance of composite materials,it was found that T6 heat treatment could affect the distribution of the second phase and the particles,the dispersed particles could improve the corrosion resistance of the material.At the same time,the rare earth element could improve the wettability of the particles and the matrix material.In future experiments,it could be considered to add rare earths to improve the segregation of particles and achieve the purpose of improving corrosion resistance.
作者
张瑞英
李金轩
杨森
闫晗
刘欢
赵鸽
Zhang Ruiying;Li Jinxuan;Yang Sen;Yan Han;Liu Huan;Zhao Ge(School of materials and Engineering,Inner Mongolia University of Technology,Hohhot 010051,China;Inner Mongolia Key Laboratory of Light Metal Materials,Hohhot 010051,China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2021年第2期194-202,共9页
Chinese Journal of Rare Metals
基金
内蒙古自然科学基金项目(2017MS(LH)0509)
内蒙古自治区高等学校科学技术研究基金项目(NJZY16086)资助。
