Bi-metallic lattice structures manufactured via an intralayer multi-material powder bed fusion method

The laser powder bed fusion technology is widely utilized for manufacturing intricate metallic components, overcoming design limitations inherent in traditional subtractive methods. Recent advancements in powder bed fusion have extended to the creation of metal multi-material structures, allowing for functionally graded and tailored properties within a single component. While functionally graded lattice structures are commonly achieved by spatially varying the relative density and/or topology of the lattice, multi-material lattices are rarely studied particularly via metal additive manufacturing where multi-material methods are a relatively recent development. This study applies an accessible enhancement to a standard powder bed fusion system for multi-material additive manufacturing, and investigates printed and heat-treated bi-metallic lattices containing regions of both 316L and 17–4PH stainless steel. The bi-material interface is examined in lattice and bulk samples, and the compression behaviour of bi-metallic lattices is investigated experimentally and computationally. The material interface is shown to be robust as built and under loading, and the bi-metallic lattices exhibit greater energy absorption than single-material samples. The inclusion of the ductile 316L in bi-metallic lattices also delays the propagation of local failure and shear bands initiated in the more brittle 17–4PH. Finite element analysis simulates the lattice compression which includes strut fracture and as-built diameters informed by computed tomography, enabling further investigation and analysis of multi-material lattice designs. This work demonstrates the benefit of multi-material additive manufacturing by providing improved performance over single-material designs.