K2Ti6O13/AZ91D镁基复合材料的组织及耐蚀性能

采用液态金属搅拌铸造法制备了K2Ti6O13晶须(PTW)增强AZ91D镁基复合材料,采用动电位极化测试和静态腐蚀试验测试了复合材料的耐腐蚀性能,并利用SEM对复合材料的表面形貌进行了观察和分析。结果表明:PTW对合金铸态组织具有明显的细化作用,而且共晶组织形貌发生明显改变,由完全离异共晶骨骼状的β相转变为部分离异共晶的蜂窝状β相。合金显微组织的细化及β相体积分数的降低,抑制了微电偶腐蚀的破坏作用,提高了AZ91D镁合金的耐蚀性能。

Microstructures and Corrosion Resistance of K2Ti6O13 Whisker Reinforced AZ91D Magnesium Matrix Composites

K2Ti6O13 whisker(PTW) reinforced AZ91D magnesium matrix composites were fabricated by a stirring casting method.The corrosion behavior of the composites was examined by potentiodynamic polarization and static corrosion tests.The surface morphology of the composites were investigated by SEM before and after corrosion tests.The results show that α-Mg grains are refined and the distribution of β phase become more uniform for the AZ91D magnesium matrix with the addition of PTW.Meanwhile,the morphologies of β phase in composites with different contents of PTW are obviously different,namely the skeletal structure of β phase is gradually transformed into partially detached honeycomb structure,and lamellar structure disappears.It can be deduced that fine α Mg grains and the decrease of β phase volume fraction lead to the inhibition of galvanic corrosion,thus increasing the corrosion resistance of the AZ91D magnesium composites.