When building up layers of different materials, the evenness of the built-up layers is of particular importance to apply a consistently thick powder layer and to minimize the mixing zones between the two materials . Depending on the material composition, material mixtures lead to undesirable, particularly brittle material compositions, which may result in cracks. Furthermore, the mechanical and physical properties of the built specimens change. One method is the optimization of the parameters of the LPBF melting process, to generate even layers. The volumetric energy density (VED) effect the density, roughness and evenness [24, 25]. It has been shown that a higher VED improves the wetting of the molten material on the surface and increases the flowability, which fills defects . Gu et al. showed that a larger melt pool has a surface smoothing effect due to an increased energy input . However, Wang et al. showed that an excessive VED leads to a higher surface roughness and to an increase of the specimen porosity . In another work it was found that the laser power, the feed rate and the combination of both have a significant influence on porosity and cracking . Another method of reducing the roughness of the individual layers is based on remelting the surfaces of the previously built-up layer before a new layer of powder is applied [29, 30].
In a first step, suitable parameters which enable a dense specimen, the flatness of the surface and minimized mixing zone to the underlying layer are searched. The parameters laser power and laser beam velocity significant effect the specimen density and crack formation  as well as the surface homogeneity and flatness. In Fig. 3, the surfaces of the final manufactured 316L specimens after ten layers are given.
To avoid these crack formations, the following methods have been successfully demonstrated or proposed in the literature: (I) increasing the heat input to reduce stress by adjusting the laser and build-up process , optimized process parameter  or using a process chamber heating, and (II) interlayer with a compatible material . An improvement should be also achieved by (III) reducing the mixed material zone and an even transition zone. The minimized roughness and thus mixing zone may lead to reduced brittle phases, minimized liquid metal embrittlement. However, this theory still needs to be proven in further studies.
The manufactured layered 316L-Bronze specimen demonstrate the feasibility of the system to produce multi-material component parts. A material mixing zone at the interface area and some micro cracks in the 316L layer have been investigated in the fabricated layered multi-material structure. The reason why the cracks result exclusively in the 316L layer is (I) the significantly higher melting point of 316L compared to bronze, which results in mixing when 316L is built-up on a bronze layer, (II) different thermal expansions, which causes cracks to build-up during solidification and (III) the infiltration of bronze into the grain structure of 316L. Approaches to reduce the formation of cracks were identified. These micro cracks needs attention for further investigations in this field. In addition, the future research work on modular LPBF system focusing on novel and innovative materials for LPBF.
Maybe, just maybe they will include more than one wheel option, kind of like the '68 and '69 Chevelle. It cracks me up how some modelers worry and fret about trivial things whenever a new tool announcement is made. Like none of us has a few extra sets of Magnum 500's sitting around anyways. I'm personally excited about this news for a number of reasons, even though the subject may not be my favorite car or even favorite Mustang I still like the body style. And as mentioned previously, any new tooling is great news, considering how very close we were very recently to losing Revell as a manufacturer altogether!!
Maybe, just maybe they will include more than one wheel option, kind of like the '68 and '69 Chevelle. It cracks me up how some modelers worry and fret about trivial things whenever a new tool announcement is made. Like none of us has a few extra sets of Magnum 500's sitting around anyways. 153554b96e