热挤压对不同搅拌时间制备的纳米SiCp/Mg-9Al-1Zn复合材料组织和性能的影响

Effect of hot extrusion on the microstructure and mechanical properties of the SiCp/Mg-9Al-1Zn nanocomposite fabricated by different stir time

摘要:

通过半固态搅拌铸造和热挤压变形复合工艺制备出了质量分数为1%的纳米SiCp/Mg-9Al-1Zn镁基复合材料。研究了搅拌时间分别为10min和30min时对纳米SiCp/Mg-9Al-1Zn镁基复合材料的显微组织和力学性能的影响。结果表明，对于铸态的纳米SiCp/Mg-9Al-1Zn镁基复合材料来说，搅拌时间为30min时，基体的晶粒细化，但在晶界处析出的Mg17Al12相数量增多，网状化严重且SiC团聚增加，使得复合材料的力学性能下降。而通过热挤压后，复合材料形成了粗晶与细晶交替的组织结构。特别是对于搅拌时间为30min的复合材料，细晶区增多且纳米SiC颗粒分布更加均匀, 这就使得力学性能高于搅拌10min的挤压态的SiCp/Mg-9Al-1Zn复合材料。

Abstract:

1wt% SiC nanoparticles reinforced Mg-9Al-1Zn magnesium matrix composite was fabricated by stir casting and hot extrusion. Effect of stirring for 10min and 30min respectively on microstructure and mechanical properties of SiCp/Mg-9Al-1Zn nanocomposite was researched. The results show that the grains of the matrix in the as-cast SiCp/Mg-9Al-1Zn nanocomposite stirring for 30min are mainly refined. But the mechanical properties of nanocomposite decline due to the increase of agglomerated SiC nanoparticles and Mg17Al12 phases with network morphology along the grain boundaries. After hot extrusion, a bimodal microstructure composed of alternate arrays of fine DRXed grains and relatively coarse DRXed grains is formed. Particularly, for as-extrusion nanocomposites stirring for 30min, the fine DRXed region can be increased and the distribution of SiC nanoparticles is more homogenous, which can exhibit superior mechanical properties compared with as-extruded SiCp/Mg-9Al-1Zn nanocomposite stirring for 10min.