Comparative strengthening of intermetallic compounds produced in situ by friction stir processing on different aluminum alloy matrixes

The composite technology based on friction stir processing (FSP) can enhance the strength of Al alloys while retaining the original toughness and ductility of Al alloys, thus achieving an improvement in the overall performance of the composites. Ni/Al composites were prepared in three typical Al matrixes by optimized FSP, and the effect of in situ generated intermetallic compounds on the strengthening of different Al substrates during the FSP was investigated. It was found that the reinforcing phase of Ni/Al composites was mainly in situ generation of Al3Ni intermetallic compound using energy dispersive spectrometry (EDS) and transmission electron microscopy (TEM), and the more the number and more uniform the distribution of Al3Ni reinforcing phase, the better the mechanical properties of Ni/Al composites. The results indicate that the Ni/Al composites formed from different series of Al alloy matrix, the Ni/6061Al composite has the most remarkable microstructure uniformity, the greatest strength increase and the least elongation decrease, which is conducive to improving its strength without affecting the processing properties of the 6061 Al alloy. The finding opens new opportunities for the preparation of Ni/Al composites with excellent properties from 6061 Al alloys.