Laser powder bed fusion of Ti-6Al-2Sn-4Zr-6Mo alloy and properties prediction using deep learning approaches

Ti-6Al-2Sn-4Zr-6Mo is one of the most important titanium alloys characterised by its high strength, fatigue, and toughness properties, making it a popular material for aerospace and biomedical applications. However, no studies have been reported on processing this alloy using laser powder bed fusion. In this paper, a deep learning neural network (DLNN) was introduced to rationalise and predict the densification and hardness due to Laser Powder Bed Fusion of Ti-6Al-2Sn-4Zr-6Mo alloy. The process optimisation results showed that near-full densification is achieved in Ti-6Al-2Sn-4Zr-6Mo alloy samples fabricated using an energy density of 77–113 J/mm3. Furthermore, the hardness of the builds was found to increase with increasing the laser energy density. Porosity and the hardness measurements were found to be sensitive to the island size, especially at high-energy-density. Hot isostatic pressing (HIP) was able to eliminate the porosity, increase the hardness, and achieve the desirable α and β phases. The developed model was validated and used to produce process maps. The trained deep learning neural network model showed the highest accuracy with a mean percentage error of 3% and 0.2% for the porosity and hardness. The results showed that deep learning neural networks could be an efficient tool for predicting materials properties using small data

Diffractive Contribution to the Elasticity and the Nucleonic Flux in the Atmosphere

We calculate the average elasticity considering non-diffractive and single diffractive interactions and perform an analysis of the cosmic-ray flux by means of an analytical solution for the nucleonic diffusion equation. We show that the diffractive contribution is important for the adequate description of the nucleonic and hadronic fluxes in the atmosphere.Comment: 10 pages, latex, 2 figures (uuencoded PostScript

In vitro study of the deployment performance of 3D printed stents in the diseased artery with the lipid arterial plaques

Atherosclerotic plaque is one of the arterial diseases which builds up in the arterial wall and can be identified by the composition of the plaque. Atherosclerosis causes the narrowing or occlusions of the arterial lumen leading to cardiovascular event. Percutaneous (keyhole) endovascular stenting has become the most common revascularisation method due to its minimum invasive nature and low complication rate. The stents, mostly fabricated by laser machines, have uniform geometries which are not ideal to treat the diseased arteries with lesion-specific properties. In addition, the effect of arterial plaque compositions on the performance of stents is not fully investigated. In this study, the deployment performance of the stents with the varied design, made of the 316L stainless steel and fabricated by additive manufacturing (AM) technology, were investigated. An in vitro experiment was conducted to test the influence of the atherosclerotic plaque compositions at 55% stenosis on the commercial and AM fabricated stents. Two artificial plaques (lipid and calcified) were prepared manually, and their mechanical testing were conducted using an unconfined compression test. Two types of stents, printed and commercial stents, were used to treat the diseased artificial artery, and the data of the pressure and diameter were collected simultaneously when the stent inflation pressure was applied. The results show that the mechanical property of the artificial lipid plaques was very similar to the real lipid plaque that observed from clinical study. From the deployment performance test for these two types of stents, it was observed that as the pressure inside of balloon increases, the diameters measured at the external wall of the artificial artery also increase when the pressure is above 4 atm. Overall, there is a close linear relationship between pressure and arterial wall movement with lipid plaque in both printed and commercial stents though that the stent made of AM technology is less flexible and has lower elastic property than the commercial one

Present and Future Experiments with Stored Exotic Nuclei at Relativistic Energies

Recent progress is presented from experiments on masses and lifetimes of bare and few-electron exotic nuclei at GSI.Comment: Proceedings of International Conference on "Frontiers in Nuclear Structure, Astrophysics and Reactions", Kos, Greece, September 12-17, 200

In situ observation of calcium oxide treatment of inclusions in molten steel by confocal microscopy

Calcium treatment of aluminum killed steel was observed in situ using high-temperature confocal scanning laser microscope (HT-CSLM). This technique along with a novel experimental design enables continuous observation of clustering behavior of inclusions before and after the calcium treatment. Results show that the increase in average inclusion size in non-calcium-treated condition was much faster compared to calcium-treated condition. Results also show that the magnitude of attractive capillary force between inclusion particles in non-treated condition was about 10−15 N for larger particles (10 µm) and 10−16 N for smaller particles (5 µm) and acting length of force was about 30 µm. In the case of calcium-treated condition, the magnitude and acting length of force was reduced to 10−16 N and 10 µm, respectively, for particles of all sizes. This change in attractive capillary attractive force is due to change in inclusion morphology from solid alumina disks to liquid lens particles during calcium treatment