Porosity, constrictivity and permeability for virtual open-cell foam microstructures

This Excel sheet contains all raw data from which plots and calculations in the referenced publication have been generated. The scope of the paper is to investigate the influence of constrictivity (a measure for bottleneck effects in microstructures) on permeability. Using a stochastic 3D microstructure model, virtual microstructures with different values of constrictivity were generated. The parameter used for controlling constrictivity is the so-called core-shell ratio. For each of the five different core-shell ratios, 10 realizations of the model were drawn for which porosity and constrictivity were computed. Subsequently, permeability was determined using the finite volume method. For three chosen structures, experimental values of permeability were gained for validation purposes. This was done by 3D printing of the structures using selective laser melting, and subsequent experimental measurement of pressure drop. Moreover, the same three structures were transformed using a more complex strut model, and permeability was compared to the values for the structures with simple strut model. The results were used to empirically derive a relationship between constrictivity and permeability

Analysis of Microstructure and Properties of a Ti–AlN Composite Produced by Selective Laser Melting

Selective Laser Melting (SLM) is a manufacturing technique that is currently used for the production of functional parts that are difficult to form by the traditional methods such as casting or CNC (Computer Numerical Control) cutting from a wide range of metallic materials. In our study, a mixture of commercially pure titanium (Ti) and 15% at. aluminum nitride (AlN) was Selective Laser Melted to form three-dimensional objects. The obtained 4 mm edge cubes with an energy density that varied from 70 to 140 J/mm3 were examined in terms of their microstructure, chemical and phase composition, porosity, and Vickers microhardness. Scanning Electron Microscopy (SEM) observations of the etched samples showed inhomogeneities in the form of pores and unmelted and partly melted AlN particles in the fine-grained dendritic matrix, which is typical for titanium nitrides and titanium aluminum nitrides. The AlN particles remained unmelted in samples, but no porosity was observed in the interface area between them and the dendritic matrix. Additionally, samples fabricated with the presintering step had zones with different sizes of dendrites, suggesting a differing chemical composition of the matrix and the possibility of the formation of the phases forming an Ti–Al–N ternary system. The chemical composition in the microareas of the samples was determined using Energy Dispersive X-Ray Spectroscopy (EDS) and revealed differences in the homogeneity of the samples depending on the SLM process parameters and the additional presintering step. The phase composition, examined using X-ray Diffraction analysis (XRD), showed that samples were formed from Ti, TiN, and AlN phases. Porosity tests carried out using a computer microtomography revealed porosities in a range from 7% to 17.5%. The formed material was characterized by a relatively high hardness exceeding 700 HV0.2 over the entire cross-section, which depended on the manufacturing conditions