Stabilization of L1<sub>2</sub> structured Cr<sub>3</sub>Cu precipitates in a Cu-4.06Cr-1.25Nb alloy with high high-temperature strength
Yinlong Yang, Qian Lei, P. Zhang, W. Y. Wang, X. K. Zhang, Yun Li, Kechao Zhou, Zhen Li
Abstract
Stable L12 structured Cr3Cu precipitates were determined in a Cu-4.06Cr-1.25Nb alloy rather than b.c.c. structured Cr precipitates by transmission electron microscope (TEM) and three-dimension atom probe tomography (3DAP) at 450 oC. The precipitation sequence of the studied alloy aged at 400 oC was supersaturated solid solution → f.c.c. Cr phase → Cr3Cu phase (L12). Nb atoms would segregate in the interface between the Cu and Cr phase, reduce the Cu/Cr interfacial energy, affect the precipitation, growth, phase transformation, and coarsening of the precipitate. These Cr3Cu precipitates significantly improved the high-temperature strength of the Cu-Cr-Nb alloy (223 ± 5 MPa at 500 oC).