Damage and microstructure analysis of high strength aluminium/Niti composite manufactured by Friction Stir Processing

Aluminium Nitinol composites are promising materials that allow creating internal stress in order to increase fracture toughness and reduce fatigue. In the past, poor bonding has been obtained by standard manufacturing techniques, but recently Friction Stir Processing (FSP) has been used to create homogeneously distributed particles and good quality bonding in a composite for low strength aluminium alloys. In the present work, microstructure and damage are investigated for high strength 7075 aluminium alloy. It was found by X-ray computed tomography that large particles tend to agglomerate in clusters and have a negative impact on composite ductility. The damage mechanisms have been observed by in situ tensile tests, and particles decohesion and shear band damage induced could be observed by digital image correlation. The understanding of particles size influences on damage and ductility is of primary importance for future applications of Al/NiTi composites.