Different effects of TiB2 particles on corrosion behaviors of in-situ TiB2/7075 composites in active and passive environments

The different effects of TiB2 on intergranular corrosion (IGC) and exfoliation corrosion (EXCO) in TiB2/7075 composites were investigated. Lower particle content accelerated IGC due to the first dissolution of large TiB2/Al interface precipitates, causing TiB2 deposition in corrosion channels. Conversely, higher particle content reduced the maximum IGC depth to 47% with dense corrosion products inhibiting penetration of corrosive solution. EXCO weight loss increased by 271% and 388% with 3.5wt.% and 7wt.% particles, respectively. Micro-galvanic corrosion and recrystallization caused by particles reduced EXCO resistance. The passive IGC environment and active EXCO environment lead to different corrosion resistances of composites.