Laser powder bed fusion additive manufacturing of highly conductive parts made of optically absorptive carburized CuCr1 powder

Fabrication of fully dense and highly conductive copper alloy parts via laser-based additive manufacturing (L-AM) is challenging due to the high optical reflectivity of copper at lambda = 1060 - 1080 nm and high thermal conductivity. To overcome this, the use of optically absorptive surface-modified copper powders is being evaluated in the laser powder bed fusion (LPBF) process. Although the surface-modified powders exhibit high optical absorption at room temperature, not all of them allow the fabrication of fully dense parts at a laser power below 500W. Accordingly, this article proposes the use of optically absorptive carburized CuCr1 powder for the consistent fabrication of copper parts. Moreover, a densification mechanism of parts is discussed to explain the distinct LPBF processing behavior of different surface-modified powders, such as carburized CuCr1 and carbon mixed CuCr1 powders, albeit having similar room temperature optical absorption. This investigation clearly outlines the advantage of a firmly bonded modified layer present on the surface of the carburized CuCr1 powder over a loosely attached carbon nanoparticle layer present in the carbon-mixed CuCr1 powder. Apart from the successful fabrication of CuCr1 parts, fabricated parts are subjected to two different post-heat treatments, and it is shown that the final properties can be customized by applying tailored post-heat treatments. (C) 2020 The Author(s). Published by Elsevier Ltd.

Automated summary

This article explores the use of optically absorptive surface-modified copper powders for fabricating fully dense and highly conductive copper alloy parts via laser-based additive manufacturing (L-AM). It discusses the densification mechanism of parts and the distinct processing behaviors of different surface-modified powders. The advantage of a firmly bonded modified layer present on the surface of carburized CuCr1 powder over a loosely attached carbon nanoparticle layer in carbon-mixed CuCr1 powder is clearly outlined, with customized final properties achievable through tailored post-heat treatments.