Stress corrosion cracking behavior of in-situ TiB2/7050 composite

The influences of the microstructure features, including TiB2 particles and grain boundaries (GBs) on the stress corrosion cracking (SCC) behavior of the extruded in situ TiB2/7050 composite have been investigated. The results of the slow strain rate testing (SSRT) show that the ultimate tensile strength, elongation and the time to failure of the specimens in 3.5% NaCl solution have reduced obviously comparing with those of the composite in the dry air. Notably, the decrease of elongation is the most obvious phenomenon, especially during the necking stage. According to the anodic dissolution and hydrogen embrittlement mechanisms, the degraded mechanical properties can be attributed to the interaction between the motion of dislocation at the crack tip and the continuous permeation of corrosive solution into the crack tip. The TiB2 particle bands have the major effects on the stress corrosion on account of the recrystallized structures, dislocations and the potential differences among the microstructure features.