Laser powder bed fusion of C18150 copper alloy with excellent comprehensive properties

Abstract

Laser powder bed fusion (LPBF) of copper alloys is expected to revolutionize aerospace propulsion and related industries. This study reports an LPBF-fabricated C18150 copper alloy with excellent comprehensive properties, e.g., thermal conductivity and tensile properties, at both room and elevated temperatures (300 °C, 500 °C). The results show that the nearly full dense specimens are obtained by using optimal process parameters. The microstructure of both the as-built (AB) specimens and the direct aging (DA) specimens at different aging temperatures (480 °C, 530 °C, and 580 °C) with a constant aging time of 4 h mainly consisted of columnar grains, and the grain size remains almost unchanged after aging treatment. The Cr precipitates grow and aggregate with the increase in the aging temperature. The highest room temperature ultimate tensile strength (UTS) of 501 MPa is obtained for specimens aged at 480 °C due to the strong precipitation strengthening effect induced by the tiny and dispersed Cr nano-precipitates. The specimens aging at 580 °C show the highest thermal conductivity of 313 W m−1 K−1 due to the recovery of lattice distortion induced by the Cr atoms dissolution. The trends in tensile properties and thermal conductivity of samples tested at 300 °C are consistent with those at room temperature. When the test temperature is 500 °C, the AB specimens achieve the highest UTS of 274 MPa and thermal conductivity of 259 W m−1 K−1 due to the in-situ precipitation of Cr atoms. This work introduces LPBF C18150 specimens with excellent comprehensive properties and promotes the application of LPBF copper alloys in the industry at different service temperatures.