热挤压变形对搅拌铸造SiCp/2024复合材料显微组织与力学性能的影响

利用搅拌铸造?热挤压工艺制备SiCp/2024复合材料板材。通过金相观察(OM)、扫描电镜(SEM)及力学性能测试等手段研究了该复合材料热挤压变形前后的显微组织与力学性能。结果表明,复合材料铸坯主要由大小为80μm~100μm的等轴晶组成,晶界第二相粗大呈非连续状分布,SiC颗粒较均匀地分布于基体合金,大部分SiC颗粒沿晶界分布,少数颗粒分布于晶内;热挤压变形后,显微孔洞等铸造缺陷和SiC颗粒团聚现象明显消除,SiC颗粒及破碎的第二相沿热挤压方向呈流线分布,复合材料的强度和塑性显著提高;拉伸断口表明,热挤压变形有利于改善SiC颗粒与基体合金的界面结合;SiCp/2024复合材料主要的断裂方式为SiC颗粒断裂和SiC/Al的界面脱粘。

Effect of hot extrusion deformation on microstructure and properties of SiCp/2024 composites by stir casting

SiCp/2024 composite hot extruded plates were prepared by stir casting and hot extrusion process.The microstructure and mechanical properties of stir cast SiCp/2024 composite before and after hot extrusion were investigated by OM,SEM and tensile test.The experimental results showed that the as-cast composite is composed of equiaxed grains with the average grain size of 80μm~100μm and the phases on the grain boundary are in large size and in discontinuity,SiC particles are distributed uniformly in matrix alloy,most of the SiC particulates locate in the inter-granular regions,only few SiC particulates are distributed within the α-Al grain.The porosity and SiC particles clustering are largely eliminated after hot extrusion,SiC particles and the secondary phases are distributed along the direction of the metal plastic flowing.Tensile test indicate that the strength and ductility of SiCp/2024 composite increase obviously after hot extrusion process.The tensile fracture surface results show that the hot extrusion deformation is helpful to improve the SiC/Al interface bonding and the fracture manner of SiCp/2024 composite is involved in SiC fracture and SiC/Al interface debonding.