Revealing trace Si effect on precipitation behavior and properties of Cu-Cr-Zr alloy: Experiments and first-principles calculations

High-performance Cu-Cr-Zr-X alloys are regarded as novel structural materials for nuclear fusion reactors. Through combining the experiments and density functional theory (DFT), the effect of Si addition on precipitation behavior and related properties of Cu-Cr-Zr-(Si) alloy was investigated for higher performance. Compared with the Si-free alloy, precipitation of Cr-rich phase is accelerated in the Cu-Cr-Zr-Si alloy (aging time < 30 min at 450 degrees C). The partial radial distribution functions of the Cu-rich matrix reveal that the formation of Si-Cr clusters is resulted from the attractive Si-Cr binding energies at the nearest-neighbor distance. Moreover, the addition of Si can reduce the Cr migration energy in Cu. At the initial stage of aging at 550 degrees C, the precipitation kinetics is dominated by temperature. By TEM analysis, it is indicated that the growth of Cr-rich phase in Cu-Cr-Zr-Si alloy is delayed, which may be attributed to the decrease of Cu/Cr interface energy due to the addition of Si, as confirmed by first-principles calculations. The optimized performance of aged Cu-Cr-Zr-Si alloy can be achieved at 450 degrees C/4 h, and Orowan strengthening is dominant. This work can provide a guideline for design of novel high-performance Cu-Cr-Zr-X alloys.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, the effect of Si addition on precipitation behavior and properties of Cu-Cr-Zr-Si alloy was investigated through experiments and theoretical calculations. The results showed that the addition of Si accelerated the precipitation of Cr-rich phase and reduced the migration energy of Cr in Cu. In addition, the addition of Si also lowered the Cu/Cr interface energy and delayed the growth of Cr-rich phase.