多道次搅拌摩擦加工对SiCP/2A14铝合金复合材料显微组织和力学性能的影响

采用搅拌摩擦加工(FSP)技术对SiC颗粒增强2A14铝合金(SiC_P/2A14)复合材料进行处理，通过金相表征、电子背散射衍射(EBSD)、SEM、硬度测试及力学拉伸实验等分析了多道次搅拌摩擦加工对SiC_P/2A14复合材料微观组织、力学性能及超塑性变形行为的影响。研究表明:经搅拌摩擦加工后，SiC_P/2A14复合材料搅拌区内SiC颗粒分布明显均匀，晶粒细化，其中2道次搅拌摩擦加工的SiC_P/2A14复合材料的晶粒尺寸最小，为3.14 μm。随着搅拌加工道次的增加，SiC_P/2A14复合材料的硬度降低，室温抗拉强度和高温延伸率均先提高后降低，其中2道次搅拌摩擦加工的SiC_P/2A14复合材料的室温抗拉强度为319 MPa，相较于未经FSP处理的SiC_P/2A14复合材料提高了41%，在500℃、应变速率为1.0×10?3 s?1条件下高温延伸率为609%，相较于未经FSP处理的SiC_P/2A14复合材料提高了133%。 

Effect of multi-pass friction stir processing on microstructure and mechanical properties of SiCP/2A14 aluminum alloy composites

The SiC particle reinforced 2A14 aluminum alloy (SiC_P/2A14) composite was treated by friction stir processing (FSP) technology. The metallurgical characterization, electron backscatter diffraction (EBSD), SEM, hardness test and mechanical tensile test were used to analyze the influence of the multi-pass FSP on the microstructure, mechanical properties and superplastic deformation behavior of the SiC_P/2A14 composite. The results show that the distribution of SiC particles in the SiC_P/2A14 composite stirring zone is obviously uniform and the grain is refined after FSP. The grain size of the SiC_P/2A14 composite with 2-pass of FSP is the smallest, which is 3.14 μm. With the increase of processing passes, the hardness of the SiC_P/2A14 composite decreases, and the tensile strength at room temperature and the elongation at high temperature both increase first and then decrease. Among them, the SiC_P/2A14 composite with 2-pass FSP reaches the peak, and the tensile strength at room temperature is 319 MPa, which is 41% higher than the SiC_P/2A14 composite without FSP, and the elongation is 609% at 500℃ and the strain rate is 1×10?3 s?1, which is 133% higher than the SiC_P/2A14 composite without FSP.