熔铸-原位合成TiC/7075Al复合材料的微观组织和凝固机制

采用熔铸-原位合成法制备了TiC/7075Al复合材料并对其微观组织和凝固机制进行了研究。原位合成复合材料中的TiC颗粒以近球形为主,平均尺寸小于700 nm。随着TiC颗粒含量的增加,复合材料的晶粒尺寸明显减小,当TiC颗粒含量为8wt%时,基体晶粒尺寸可以减小至10μm左右。熔体反应过程中,随着TiC增强相颗粒含量的增加,凝固前沿的流体的粘度增加,降低了TiC颗粒的临界裹入速度,同样在反应时降低温度将增加熔体的粘度,有利于TiC颗粒的裹入。

Microstructure and solidifying mechanism of TiC/7075 aluminium composite prepared by melt in-situ synthesis

The TiC/7075 aluminium composites were synthesized by melt in-situ reaction method and the microstructure and solidifying mechanism of the composites were studied.The TiC particles are nearly spherical and their average size is less than 700 nm.The grain sizes of the composite are significantly reduced with the increasing of TiC particles content.The matrix grain sizes could be reduced to about 10 μm when TiC particles content is 8wt%.With the increasing of the content of TiC reinforced phase particles during reaction in melt,the viscosity of the solidifying front fluid is increased,which causes to decreasing of the critical coating rate.In addition,reducing the melt temperature would be propitious to increase the fluid viscosity,which would be helpful for the coating of the TiC particles.