Ultrafast regulation of nano-scale matrix defects using electrical property discrepancies to delay material embrittlement

Abstract

Nano-scale phases can enhance or reduce the mechanical properties of materials, so it is very important to control the size of the phases. Copper-rich nanoclusters as matrix defects will significantly reduce the performance of materials for key nuclear power components, while traditional heat treatment method has a technical bottleneck for the dissolution of nanoclusters. A new method of using the inherent electrical property discrepancies between the matrix material and the nanoclusters to effectively dissolve the nanoclusters through pulsed electric current to realize the recovery of material aging degradation performance is proposed. The performance evolution of simulated steel in the aging-external field repair cycle was studied, and it was found the dislocations as the preferred nucleation sites of nanoclusters were regulated in virtue of the non-thermal effect of current, resulting in a decrease in dislocation density and entanglement release. In the subsequent thermal aging process, the embrittlement rate of the aged and tempered material trained by the electric pulse was slower than that of the untreated sample. When moving dislocations are pinned by nanoclusters under high stress, nano-scale dislocations can be induced into the clusters. The dislocations near the nanoclusters and the newly formed nano-scale dislocations in the nanoclusters act as fast diffusion channels, which can further accelerate the dissolution of the nanoclusters.