SiCp/LD2复合材料焊缝组织及性能

采用Al—Mg及Al-Si两种焊丝分别对SiCp／LD2复合材料进行了MIG焊，利用光镜、电镜及MTS-810试验机对焊缝的组织及性能进行了分析，结果表明，采用Al-Mg焊丝焊接时，熔池中Al—SiC间的界面反应程度均较大．生成了较多的针状Al4C3，且Al4C3的尺寸较大。采用Al-Si焊丝时，MIG焊熔池中的界面反应程度显著降低，仅生成了少量尺寸较小的针状Al4C3；利用Al—Si焊丝还可有效地防止焊缝熄弧处的宏观结晶裂纹。力学性能试验表明，用Al-Si焊丝焊接的接头强度比用Al—Mg焊丝焊接的接头强度高。

Microstructure and Mechanical Properties of Weld Metal of SiCP/LD2 Composite

The SiCP/ LD2 alloy composite was welded by using MIG with addition of Al-Si or Al-Mg filler metal. The mi- crostructure of weld metal was analysed with OM and TEM, and the properties of weld metal were analysed with MTS-810 testing system. The results show that when welding with Al-Mg filler metal, serious reaction between Al matrix and SiC particles occurred in the molten pool, and a quantity of large -size acicular Al4C3 formed in the weld metal. With Al-Si filler metal used, the interfacial reaction between Al matrix and SiC particles is alleviated remarkable, only a little small-size acicular Al4C3 is found in the MIG weld, It is also found that Si in welding wire can prevent from the formation of hot-crack in weld. The mechanical testing results show that tensile strengths and elongation of welds deposited with Al-Si filler metal is higher than those of welds deposited with of Al-Mg filler metal.