Enhancing high-temperature properties in laser powder bed fusion of Cu-Cr-Zr alloy via heat-stable dislocations and dual-nanoprecipitates

Abstract

Commercial wrought high-strength Cu-Cr-Zr alloys face limited high-temperature properties due to the rapid coarsening or dissolution of Cr precipitates. Here, we report a laser powder bed fusion (LPBF) fabricated Cu-0.84Cr-0.42Zr (wt.%) alloy with exceptional heat resistance after aging. Primary Cr@Cu₅Zr phase (∼39.8 nm) with core-shell structure and a high density of heat-stable dislocations were introduced from the rapid solidification of LPBF and enabled the alloy to gain significant improvement in high-temperature properties. After aging treatment, secondary Cr and Cu₅₁Zr₁₄ phases (∼3.4 nm) were precipitated, in which Zr solute was segregated at one side of the Cr phase, enhancing the thermal stability of Cr phase. The excellent combinations of strength and thermal conductivity were achieved at or above 400°C. Particularly at 600°C, the aged sample not only exhibited a high tensile strength of ∼196 MPa, which significantly surpassed that of wrought Cu-Cr-Zr alloys, but also possessed a thermal conductivity of ∼349 W/(m K) comparable to that of pure copper.