Laser powder bed fusion processing of Cu-Invar continuous gradient alloys with controllable thermal-mechanical properties

The integration of immiscible Cu and FeNi systems poses significant challenges in achieving defect-free interfaces and thermomechanical compatibility due to significant thermal mismatch stress. In this work, we propose a continuous gradient alloy micro laser powder bed fusion (CGA-μLPBF) strategy with material gradients in different degrees of freedom to address interfacial stress concentration and elemental distribution. Based on high-throughput experimental results and thermodynamic calculations, we have achieved theoretically-predicted optimal precipitation strengthening without the formation of cracks and intermetallic compounds and realised a continuous variation in the Coefficient of Thermal Expansion (CTE). The CTE of the as-printed CGA samples varies continuously from 1.4 × 10−6/K to 11 × 10−6/K at 100℃, resulting in difference in thermal strains of more than tenfold between the two ends without any cracking. It simultaneously exhibits continuously thermal expansion and thermal diffusion performances within the same component. The compositional continuous gradient alloys exhibit remarkable potential for applications in precision instruments and thermal management applications, offering a unique combination of thermomechanical performance and design flexibility. These findings highlight the unique capabilities of CGA-μLPBF in producing advanced materials for next-generation electronic devices.