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Manufacturing defects, such as porosity and inclusions, can significantly compromise the structural integrity and performance of additively manufactured parts by acting as stress concentrators and potential initiation sites for failure. This paper investigates the effects of pore system morphology (number of pores, total volume, volume fraction, and standard deviation of size of pores) on the material response of additively manufactured Ti6Al4V specimens under a shear–compression stress state. An automatic approach for finite element simulations, using the J2 plasticity model, was utilized on a shear–compression specimen with artificial pores of varying characteristics to generate the dataset. An artificial neural network (ANN) surrogate model was developed to predict peak force and failure displacement of specimens with different pore attributes. The ANN demonstrated effective prediction capabilities, offering insights into the importance of individual input variables on mechanical performance of additively manufactured parts. Additionally, a sensitivity analysis using the Garson equation was performed to identify the most influential parameters affecting the material’s behaviour. It was observed that materials with more uniform pore sizes exhibit better mechanical properties than those with a wider size distribution. Overall, the study contributes to a better understanding of the interplay between pore characteristics and material response, providing better defect-aware design and property–porosity linkage in additive manufacturing processes.

A semi-solid route is expected to be a fabrication method that can fabricate aluminum alloy foams with a variety of mechanical properties, but the allowance fluctuation of the fabrication conditions of aluminum alloy foams with high reproducibility is not clear. The objective of this study was to reveal the allowance fluctuation between the setting temperature and the actual temperature of the melt to fabricate stable foams, having pores with small pores and high circularity, and the influence of the increasing volume fraction of the solid on the pore morphology. Al-Si alloy foams were fabricated five times by adding a blowing agent into a semi-solid slurry under the same setting fabrication conditions, such as the temperature and concentration of oxygen in the atmosphere. The results of small relative standard deviations of pore diameter and circularity indicated that the conducted fabrication process had high reproducibility, even if the volume fraction of the solid changed in a range of 5%. When the volume fraction of the solid exceeds the minimal fraction of primary crystals for prevention of drainage, the clogging effect works more efficiently because the ratio of clogged cell walls increases. Additionally, the preferred range of the volume fraction of the solid for the fabrication of stable foam was revealed to be around 15% to 35%.

Closed-cell aluminum foam has a porous structure and metal properties due to its unique composition. As a structural material, it has the advantages of being lightweight, having a large specific surface area, and having high specific strength and stiffness. As a functional material, it can be used for sound and noise reduction, heat insulation, electromagnetic shielding, damping, and energy absorption, but it also has poor mechanical properties and poor surface flatness, and can be easily corroded. Considering the abovementioned problems, researchers have gradually extended their research on foam materials. Under the research of many international scholars, studies have shifted from simple aluminum foam preparation to improving and optimizing aluminum foam composite structures (AFCSs). From the perspective of development prospects, AFCSs have better application prospects than single aluminum foam. In this paper, the research progress on the preparation technology of AFCSs in recent years was reviewed based on the performance enhancement mechanism of aluminum matrix composites and the structural characteristics of aluminum foam. The morphology and pore structures of closed-cell AFCSs under different preparation methods were summarized. However, due to the limitations of existing experimental conditions, this paper only considered the advantages and disadvantages of AFCS preparation methods. The improvement of AFCS preparation technology, the development of the potential properties of AFCSs, and the promotion of AFCS industrial applications were also considered.

This paper analyzes the pore morphology of two different concrete mixtures (plain and fiber-reinforced) under two different curing conditions, through the use of a CT scanner and post-processing software. Twelve cylinders of 45.2 mm in diameter and 50 mm in height were cast. Half of the specimens were kept in a humidity-controlled room, at 20 °C and 60% humidity, and the rest in a curing room, at 20 °C and 100% humidity. All the specimens were scanned at the age of 28 days, using a micro CT scanner. The results reveal that the presence of fibers substantially modifies the pore morphology in the way of increasing the volume of voids and the pore-size, reducing the shape factor of the voids and reorienting the voids toward a direction more aligned to the one showed by the fibers. In general, the curing conditions do no exhibit a great impact on the results.

We investigated pore formation in aluminum foams by controlling primary crystal morphology using three master alloys. The first one was a direct chill cast A2024 (Al-Cu-Mg) alloy (DC-cast alloy). The others were A2024 alloys prepared to possess fine spherical primary crystals. The second alloy was made by applying compressive strain through a Strain-Induced Melt-Activated process alloy (SIMA alloy). The third one was a slope-cast A2024 alloy (slope-cast alloy). Each alloy was heated to either 635 °C (fraction of solid fs = 20%) or 630 °C (fs = 40%). TiH2 powder was added to the alloys as a foaming agent upon heating them to a semi-solid state and they were stirred while being held in the furnace. Subsequently, A2024 alloy foams were obtained via water-cooling. The primary crystals of the DC-cast alloy were coarse and irregular before foaming. After foaming, the size of the primary crystals remained irregular, but also became spherical. The SIMA and slope-cast alloys possessed fine spherical primary crystals before and after foaming. In addition to average-sized pores (macro-pores), small pores were observed inside the cell walls (micro-pores) of each alloy. The formation of macro-pores did not depend on the formation of the primary crystals. Only in the DC-cast alloy did fine micro-pores exist within the primary crystals. The number of micro-pores in the SIMA and slope-cast alloys was one third of that in the DC-cast alloy.

A2024 alloy foams were fabricated by two methods. In the first method, the melt was thickened by Mg, which acts as an alloying element (melt route). In the second method, the melt was thickened by using primary crystals at a semi-solid temperature with a solid fraction of 20% (semi-solid route). A2024 alloy foams fabricated through the semi-solid route had coarse and uneven pores. This led to slightly brittle fracture of the foams, which resulted in larger energy absorption efficiency than that of the foams fabricated through the melt route. Moreover, A2024 alloy foams fabricated through the semi-solid route had a coarser grain size because of the coarse primary crystals. However, by preventing the decrease in the alloying element Mg, the θ/θ’ phase was suppressed. Additionally, by preventing the precipitation of the S′ phase, the amount of Guinier-Preston-Bagaryatsky (GPB) zone increased. This resulted in a larger plateau stress.