高密度脉冲电流下Cu-SiC_p/AZ91D复合材料的组织及力学性能分析

Analysis of Microstructure and Mechanical Properties of Cu-SiC_p/AZ91D Composites under High Density Pulsed Current

研究了高密度脉冲电流(EP)下Cu-SiCp/AZ91D复合材料凝固组织的细化机理。分析了EP对Cu-SiCp/AZ91D复合材料组织演化及力学性能的影响。结果表明:施加EP后深灰色基体与浅灰色枝晶形成的网状组织变得浓密,晶粒细化显著。Mg2Si相沿β-Mg17Al12枝晶下方生长,Mg2Si周围组织由浅灰色α-Mg和Al4C3混合组成,同时伴随少量Cu在枝晶上方,β-Mg17Al12枝晶减少。添加Cu-Si Cp颗粒后AZ91D镁中β-Mg17Al12的衍射峰消失,Mg2Si相的衍射峰得到增强。施加EP可以有效抑制Si Cp偏聚,使Si Cp能与熔体一起处于均匀混合状态。添加Cu-SiCp后,材料的力学性能得到明显提升,但伸长率却降低。Cu-SiCp/AZ91D具有更致密的断口组织,EP作用下,Cu-SiCp/AZ91D断口韧窝更加细小。添加Si C颗粒后基底硬度发生较小幅度的提升;施加EP后,硬度得到明显的提升。

The solidification microstructure refinement mechanism of Cu-SiCp/AZ91D composites under high density pulse current(EP)was studied.The effects of EP on the microstructure evolution and mechanical properties of Cu-SiCp/AZ91D composites were analyzed.The results show that after the application of the EP,the microstructure of the dark gray matrix and the light gray dendrites becomes dense and the grain refinement is significant.The Mg2Si phase grows along the lower part of theβ-Mg17Al12dendrite,the surrounding tissue of the Mg2Si consists of a mixture of light grayα-Mg and Al4C3,theβ-Mg17Al12dendrites with a small amount of Cu above the dendrite.The diffraction peak ofβ-Mg17Al12in Z91D magnesium disappears after the addition of Cu-Si Cpparticles.The application of EP can effectively inhibit Si Cpsegregation,so that Si Cpcan be in a homogeneous mixed state with the melt.After adding Cu-SiCp,the mechanical properties of the material are improved obviously,but the elongation decreases.Cu-SiC/AZ91D has a more dense fracture structure,under the action of EP,the fracture dimples of Cu-SiCp/AZ91D are finer.The increase of the substrate’s hardness after the addition of Si C particles.After the application of EP,the hardness is obviously improved.