Significant improvement in creep resistance of Cu-Cr-Zr alloys induced by trace Si

Abstract

To adapt to harsher fusion circumstance, it is of great importance to develop a new generation of Cu-Cr-Zr-X alloy with good creep resistance for divertor in DEMO or CFETR. In this paper, the effects of Si addition on microstructural evolution and creep behavior of Cu-Cr-Zr alloy was investigated under varying applied stresses (50–150 MPa) at 450 °C and 550 °C. The present results reveal that the steady-state creep rate of Cu-Cr-Zr alloys ranges from 10⁻¹⁰ to 10⁻⁹ s⁻¹ at 450 °C and from 10⁻⁸ to 10⁻⁶ s⁻¹ at 550 °C under varying stresses. In comparison, Si-containing alloys maintain a steady-state creep rate of 10⁻¹⁰ s⁻¹ at 450 °C and span only two orders of magnitude, ranging from 10⁻⁹ to 10⁻⁸ s⁻¹ at 550 °C. In addition, the creep life of alloys containing Si is significantly higher than that of alloys without Si under identical conditions. This suggests that the creep resistance of Cu-Cr-Zr alloy can be enhanced by adding Si, primarily due to the synergistic effect of nano-sized Cr precipitates, which exhibit limited growth and stable Cr₃Si intermetallic phase. These features help pin dislocation and grain boundaries, thereby obstructing their motion. This work provides theoretical guidance for the development of new creep-resistant alloys for use in the fusion field.