联合添加微量Sc、Zr元素对B4C/7075Al复合材料力学性能和腐蚀行为的影响

Effect of Combined Addition of Trace Sc and Zr Elements on Mechanical Properties and Corrosion Behavior of B4C/7075Al Composite

限制高强度B4C/Al复合材料工程应用的关键为腐蚀问题,添加微量合金元素是提高其耐蚀性的有效措施。采用压力浸渗法制备了B4C/7075和添加微量Sc、Zr元素的B4C/7075-0.15Sc-0.35Zr复合材料,利用扫描电镜、透射电镜、弯曲性能测试、拉伸性能测试、中性盐雾试验和电化学测试对比研究了联合添加Sc和Zr元素对B4C/7075Al复合材料的显微组织、力学性能和腐蚀行为的影响。结果表明:添加Sc和Zr元素后,复合材料的抗弯曲强度和抗拉强度升高,腐蚀速率降低,腐蚀电流密度(Jcorr)下降,耐蚀性增强,这是因为添加Sc和Zr元素后,复合材料的晶界析出相细小且不连续分布,无析出带(PFZ)消失。

The key to restrict the engineering application of high-strength B4C/Al composites is corrosion,and adding trace alloying elements is an effective measure to improve corrosion resistance.In this work,the B4C/7075 and B4C/7075-0.15Sc-0.35Zr composite containing trace Sc and Zr elements were prepared by pressure infiltration.The influence of combined addition of Sc and Zr on microstructure,mechanical properties and corrosion behavior of B4 C/7075 composites was investigated by using scanning electron microscopy,transmission electron mi-croscopy,bending performance testing,tensile performance testing,neutral salt spray testing and electrochemical testing.Results showed that adding Sc and Zr elements to B4 C/7075 composites,the higher bending strength and tensile strength values were obtained in B4 C/7075-0.15Sc-0.35Zr.In addition,the corrosion rate and the corrosion current(Jcorr)decreased,indicating that the corrosion resistance of B4 C/Al composite increased,which might be caused by that the grain boundary precipitates in the composite material were small and discontinuous after adding Sc and Zr elements,and the precipitate free zone(PFZ)disappeared.