A promising approach to 3D printing of metal foam with defined porosity

Metal foams, which are similar to other types of foam materials, are composed of solid material with a significant proportion of the volume consisting of pores. Although metal foams retain some of the properties of the original material, they also possess several advantageous characteristics such as low density and thermal conductivity, high specific stiffness, and porosity. As a result, metal foams are becoming increasingly popular for applications such as heat exchangers, soundproofing devices, and gas–liquid filters. Additive manufacturing has the potential to expand the production capabilities of foams by reducing materials consumption and the creation of complex geometry. This work demonstrates the possibility of direct 3D printing of metal foams made of titanium, aluminum, and aluminum-bronze using direct energy deposition and special parameters of the printing process. This method is superior to traditional methods in terms of cost and the absence of additional stages of preparation and post-processing. The open porosity of the foam can be easily changed by varying the laser power. The laser power in the range of 10 to 180 W along with rapid prototyping makes it possible to obtain metal foams of complex geometry with a high degree of open porosity (up to 50% for titanium and up to 30% for aluminum alloys), not inferior in quality to foams obtained by conventional methods. Moreover, by changing the printing modes, it is possible to adjust the structure of foam from uniform to columnar, increasing the thermal conductivity and insulating properties of the samples.