Feasibility and Safety of Intraoperative Optical Coherence Tomography-Guided Short-Term Posturing Prescription after Macular Hole Surgery.

PURPOSE: To assess closure rate and visual outcome of a court of patients with macular hole (MH) who underwent surgical repair with intraoperative optical coherence tomography (iOCT)-confirmed MH closure and short-term postoperative face-down posturing (FDP). Secondary aim was to assess the correlation between iOCT and postoperative OCT at day 1. METHODS: Retrospective clinical study conducted in the Miulli Hospital Acquaviva delle Fonti (Italy), enrolling patients with idiopathic MH who underwent 25-G pars plana vitrectomy plus internal limiting membrane peeling. During surgery, closure of MH was confirmed by iOCT and short-term FDP (12-24 h, until day-1 visit) was prescribed. All patients had measurement of best-corrected visual acuity (BCVA) and spectral domain-OCT before the surgery and during follow-up (at 1 day, 1 month, 3 months). RESULTS: Twenty-nine eyes of 29 patients (14 males, 62.1%) were enrolled in the study. MH mean size was 451.7 ± 139.7 µm and baseline BCVA was 0.77 ± 0.26 logarithm of the minimum angle of resolution (LogMAR). MH was confirmed to be closed in 100% of patients intraoperatively (iOCT) and at OCT during early follow-up (1-3 days). Mean time of FDP was 18 ± 2.6 h. At 3 months, MH closure rate was 93%; 2 eyes -underwent secondary MH repair surgery. Final BCVA was 0.39 ± 0.22 LogMAR (p < 0.0001). CONCLUSION: iOCT-based confirmation of MH closure could be a safe and useful tool for prescribing short-term FDP after surgery, with high closure rate and no additional complication. The execution of an OCT in the immediate postoperative days could be potentially unnecessary.

COMPARATIVE ANALYSIS OF RETINAL REATTACHMENT SURGERY WITH OR WITHOUT INTERNAL LIMITING MEMBRANE PEELING TO PREVENT POSTOPERATIVE MACULAR PUCKER.

PURPOSE: To determine whether internal limiting membrane (ILM) peeling during pars plana vitrectomy for rhegmatogenous retinal detachment reduces the incidence of epiretinal membrane (ERM) formation. METHODS: In this retrospective study, preoperative, intraoperative, and postoperative data from all eyes undergoing pars plana vitrectomy for rhegmatogenous retinal detachment between January 2007 and December 2013 was analyzed. All cases with at least 1-year of follow-up were included. Data collection included vision, intraoperative complications, occurrence of ERM, and spectral domain optical coherence tomography characteristics. The OCTs were retrieved for all eyes and were graded by a single masked grader. RESULTS: Out of 159 eyes recruited, ILM peeling was done in 78 eyes (49%). Overall occurrence of ERM was 20%. Seven eyes (9%) in ILM peeling group and 25 eyes in the non-ILM peeling group (31%) showed ERM (P = 0.001). Postoperative vision was significantly better in eyes that had ILM peeling (0.48 ± 0.4 logarithm of the minimum angle of resolution [20/63] vs. 0.77 ± 0.6 logarithm of the minimum angle of resolution [20/125], P = 0.003). In multivariable models adjusting for type of tamponade, ILM peeling reduced the likelihood of ERM formation by 75% (P = 0.01). CONCLUSION: Internal limiting membrane peeling during pars plana vitrectomy for rhegmatogenous retinal detachment significantly reduces ERM formation in the postoperative period and is associated with better visual and anatomical outcomes.

All-in-One Cellulose Nanocrystals for 3D Printing of Nanocomposite Hydrogels.

Cellulose nanocrystals (CNCs) with >2000 photoactive groups on each can act as highly efficient initiators for radical polymerizations, cross-linkers, as well as covalently embedded nanofillers for nanocomposite hydrogels. This is achieved by a simple and reliable method for surface modification of CNCs with a photoactive bis(acyl)phosphane oxide derivative. Shape-persistent and free-standing 3D structured objects were printed with a mono-functional methacrylate, showing a superior swelling capacity and improved mechanical properties.

Effects of vitamin B12 on the corneal nerve regeneration in rats.

The study was designed to investigate the effects of a new ophthalmic solution containing 0.05% vitamin B12 0.05% on corneal nerve regeneration in rats after corneal injury. Eyes of anesthetized male Wistar rats were subjected to corneal injury by removing the corneal epithelium with corneal brush (Algerbrush). After the epithelial debridement, the right eye of each animal received the instillation of one drop of the ophthalmic solution containing vitamin B12 0.05% plus taurine 0.5% and sodium hyaluronate 0.5% four time per day for 10 or 30 days. Left eyes were used as control and treated with solution containing taurine 0.5% and sodium hyaluronate 0.5% alone following the same regimen. Fluorescein staining by slit-lamp and morphological analysis was used to determine corneal wound healing. Immunohistochemistry, immunoblot and confocal microscopy were used to examine corneal re-innervation. Slit-lamp and histological analyses showed that re-epithelization of the corneas was accelerated in rats treated with vitamin B12. A clear-cut difference between the two groups of rats was seen after 10 days of treatment, whereas a near-to-complete re-epithelization was observed in both groups at 30 days. Vitamin B12 treatment had also a remarkable effect on corneal re-innervation, as shown by substantial increased in the expression of neurofilament 160 and ß-III tubulin at both 10 and 30 days. The presence of SV2A-positive nerve endings suggests the presence of synapse-like specialized structures in corneal epithelium of the eye treated with vitamin B12. Our findings suggest that vitamin B12 treatment represents a powerful strategy to accelerate not only re-epithelization but also corneal re-innervation after mechanical injury.

Real-world experience with fluocinolone acetonide intravitreal implant in patients with diabetic macular edema.

OBJECTIVES: to evaluate long-term effectiveness and safety of fluocinolone acetonide (FAc) implant used as second-line treatment in patients with persistent diabetic macular edema (DME). METHODS: retrospective data chart review of 241 pseudophakic eyes of 178 patients treated with FAc from July 2017 to December 2021 in 10 medical retinal units in Italy. The primary endpoint was the change of best-corrected visual acuity (BCVA) and central macular thickness (CMT) at 2 years. A Student's paired t-test was used. Additional therapies for DME and intraocular pressure (IOP)-related events were also evaluated. RESULTS: efficacy of FAc was assessed in a subset of 111 eyes with at least 24 months of follow-up. Mean BCVA increased at 2 years by 5.1 ETDRS letters (95%CI = 2.6-7.5; p < 0.001) while mean CMT decreased by 189 µm (95% CI 151-227; p < 0.001). Thirty-eight of these eyes (34.2%) needed additional intravitreal treatments, mainly anti-VEGF. Safety was evaluated on the entire cohort of 241 eyes treated with FAc. Overall, 66 eyes (27.4%) required emergent IOP-lowering medications (typically within the first-year post FAc) while 14 eyes (5.8%) underwent trabeculectomy, mostly during the second year of follow-up. CONCLUSION: FAc implant provides a substantial long-term functional and anatomical benefit when used as second-line treatment in eyes with DME. IOP rise can be adequately managed with topical agents although some eyes may require IOP-lowering surgery.

Study of vitamin D penetration in the human aqueous after topical administration.

PURPOSE: this study was designed to measure the concentration of Vitamin D in the aqueous and to investigate if its topical application can increase quantities in aqueous humor. METHODS: 29 patients scheduled for cataract surgery were divided into two groups. Group 1 was used as a control group, in group 2 patients were instructed to instill one drop of vitamin D eye drops three times daily 10 days before surgery .Aqueous humor was collected with a 30-gauge needle immediately before surgery. Vitamin D concentrations were analyzed by liquid chromatography tandem mass spectrometry. RESULTS: Aqueous humor (AH) samples in both groups had small but detectable vitamin D levels. In the AH concentrations of vitamin D were, respectively, 2.1ng/mL 0.4 in group 1 and 2.1ng/mL0.3 in group 2(P = 0.9). CONCLUSION: Our study confirmed the presence of vitamin D in AH. No significant difference of vitamin D concentration in AH was observed between the treatment and control group.

Effect of intravitreal dexamethasone implant in treatment-naive and previously-treated patients with diabetic macular edema.

PURPOSE: To document the effects of intravitreal dexamethasone implant on retinal microvasculature in patients with diabetic retinopathy complicated by center-involving macular edema. METHODS: 35 eyes of 35 patients affected by retinopathy due to type 2 diabetes (15 treatment-naïve and 20 previously treated) were included in this retrospective study with a follow-up of 4 months. Foveal avascular zone (FAZ) area and superficial capillary plexus (SCP) and deep capillary plexus (DCP) densities in the foveal and parafoveal areas were measured by optical coherence tomography angiography (OCTA) at baseline and 2 and 4 months post-injection. Intraocular pressure, morphological and functional parameters were evaluated. RESULTS: a significant difference was found in both groups at 2 months after injection in terms of functional (BCVA, p < 0.05) and morphological (CMT, p < 0.05) parameters. During follow-up, FAZ area, SCP, and DCP in the foveal and parafoveal areas did not change significantly. CONCLUSIONS: intravitreal dexamethasone implant is effective in the treatment of diabetic center-involving macular edema and was associated with significant improvements in BCVA and CMT at 2 months after injection. After a single dexamethasone implant injection, FAZ area and retinal vascular density does not show significant variations in both naive and non-naive DME patients subgroups.

Success of iOCT in surgical management of ERM peeling.

PURPOSE: Epiretinal membranes (ERM) are a disorder leading to progressive vision loss and metamorphopsia. The ERM is treated through a pars-plana vitrectomy (PPV) with membrane peeling. The aim of this study was to define the success of intraoperative optical coherence tomography (iOCT) in ERM surgery to standard surgical visualization techniques and enhance our current approach to clinical practice. METHODS: This study included 56 eyes of 54 patients who underwent surgical intervention for management of idiopathic ERM. Patients were recruited between February 2018 and March 2020 at "Francesco Miulli" Hospital ophthalmology department in Acquaviva delle Fonti, Bari, Italy. RESULTS: in 28 eyes, ERM peeling was performed without staining and without iOCT; 25% of these eyes peeling ERM (n = 7) was performed easily, while 75% of eyes peeling ERM (n = 21) was not possible without staining and was necessary staining with Brillant Blu G.In 28 eyes ERM peeling were performed with iOCT; in 92.5% of these eyes (n = 26) ERM peeling was easily done without staining, while in 7.5% of this group of eyes (n = 2) ERM peeling was not possible without staining. CONCLUSIONS: Our study shows how iOCT has successfully assisted the surgeon to complete peeling in most of the cases treated without the use of a chromovitrectomy dye; in flat ERM was more difficult and iOCT failed to visualize the inner limiting membrane (ILM).

Clinical course of choroidal neovascular membrane in West Nile virus chorioretinitis: a case report.

BACKGROUND: This report describes the clinical course of choroidal neovascular membrane (CNV) in West Nile virus-associated chorioretinitis. CASE PRESENTATION: A 28-year-old Italian woman was referred to our institution because of reduced visual acuity in the left eye dating back 4 months. A diagnosis of retinal vasculitis in the right eye and chorioretinitis with CNV in the left eye was made. A complete workup for uveitis revealed positivity only for anti-West Nile virus immunoglobulin M (IgM), while immunoglobulin G (IgG) was negative. Whole-body computed tomography and nuclear magnetic resonance imaging of the brain were also negative. Therefore, the patient was treated with a combination of oral prednisone (starting dose 1 mg/kg per day) and three intravitreal injections of bevacizumab 1.25 mg/0.05 ml, 1 month apart. Fourteen days from starting corticosteroid therapy and after the first intravitreal injection, the patient experienced increased visual acuity to 0.4. Response to therapy was monitored by clinical examination, ocular coherence tomography (OCT), OCT angiography and retinal fluorescein angiography. Three months later, resolution of CNV in the left eye was achieved and no signs of retinal vasculitis were detected in the right eye, while serum IgM for West Nile virus turned negative and IgG positive. CONCLUSION: CNV may be a complication of West Nile virus-associated chorioretinitis, and only subclinical retinal vasculitis may also be found even in non-endemic regions.

A357 Alloy by LPBF for Industry Applications.

The aim of this study is to define the process parameters to build components for industrial applications in A357 alloy by Laser Powder Bed Fusion (LPBF) and to evaluate the effects of post-processing heat treatments on the microstructure and mechanical properties in order to obtain the highest hardness and strength. First, process parameters values were defined to obtain full dense components with highest productivity. Then samples were built for microstructural, hardness, and tensile strength investigation in different conditions: as-built, after a stress-relieving treatment, and after a T6 precipitation hardening treatment. For this latest treatment, different time and temperatures for solution and ageing were investigated to find the best in terms of final hardness achievable. It is demonstrated that samples in A357 alloy can be successfully fabricated by LPBF with a density of 99.9% and a mean hardness value achievable of 116 HV0.1, in as-built condition. However, for production purposes, it is fundamental to reduce the residual stresses typical of LPBF. It was shown that a similar hardness value could be obtained after a stress-relieving treatment followed by a proper T6 treatment, together with a coarser but more isotropic microstructure.

PROGRESSION OF RETINAL ISCHEMIA IN A CASE OF MACULAR TELANGIECTASIA TYPE 1 AFTER RANIBIZUMAB INJECTION: OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY FINDINGS.

PURPOSE: To describe a case of a 68-year-old man with macular telangiectasia (MacTel) Type 1 in the right eye, showing an increase in capillary ischemia after intravitreal ranibizumab. METHODS: The patient underwent complete ophthalmologic evaluation, including best-corrected visual acuity, intraocular pressure, anterior segment and fundus examination, optical coherence tomography (OCT), and OCT angiography at baseline and on each visit. Fluorescein angiography was performed at baseline. The patient was followed up on monthly bases for 22 months. RESULTS: The patient presented a best-corrected visual acuity of 20/80 in the right eye and of 20/25 in the left eye at baseline. In the right eye, the fluorescein angiography images showed perifoveal capillary ectasia, late-frames dye leakage, and enlargement of the foveal avascular zone. The OCT showed intraretinal pseudocysts and microaneurysms, and the OCT angiography showed vascular rarefaction, capillary dropout, and capillary ectasia of the superficial plexus. After 16 months of follow-up and four ranibizumab injections, the best-corrected visual acuity was 20/60, and the OCT angiography disclosed a further enlargement of the foveal avascular zone area and increased capillary obliteration in the perifoveal nasal area. CONCLUSION: Optical coherence tomography angiography may represent an indispensable diagnostic technique, complementary to traditional imaging, in the evaluation of the effects of anti-vascular endothelial growth factor therapy in patients with MacTel Type 1.

Spontaneous resolution of optic pit maculopathy: an OCT report.

The separation of the vitreous from the optic nerve head and the macula plays a primary role in the spontaneous resolution of optic disc pit (ODP) maculopathy. Optical coherence tomography (OCT) helps in the non-invasive monitoring of this condition, when treated conservatively. The aim of this report was to describe a pediatric case of spontaneously resolved ODP maculopathy, managed conservatively and monitored by means of spectral domain (SD)-OCT. A 14-year-old girl presented with severe visual loss in the right eye (RE). Fundus examination demonstrated a temporal ODP with altered foveal reflex. The SD-OCT B-scans revealed severe intraretinal schisis-like changes, broad vitreal adhesion in the optic nerve head area, posterior hyaloid thickening, and vitreal entrapment in the premacular space. The patient was managed conservatively. Spontaneous resolution of ODP maculopathy took place over 3 months, with vision improved up to 1.0 (Snellen charts). The macular schisis progressively resolved after posterior vitreous detachment. In conclusion, in our report, a complete restoration of the foveal anatomy was achieved without any surgical intervention. This OCT-based report confirms the role of the vitreomacular abnormalities in the pathogenesis of the disease.

Escherichia coli keratitis treated with ultraviolet A/riboflavin corneal cross-linking: a case report.

PURPOSE: To describe a case of keratitis caused by the Gram-negative Escherichia coli, treated with UVA-riboflavin cross linking. METHODS: Case report. RESULTS: A 78-year-old woman with diabetes presented with a 1-week history of pain, photophobia, foreign body sensation, and lacrimation in the right eye. The patient underwent topical and systemic antimicrobial therapy, without improvement. The authors treated the patient with riboflavin and corneal UVA crosslinking, with the aim to promote healing of the ulceration. One day after the procedure, the corneal ulceration was covered by cicatricial tissue, and the patient reported a significant improvement in symptoms. One month after the treatment, corneal edema was almost completely resolved, corneal ulceration was healed, and the painful symptoms of the patient had disappeared. CONCLUSIONS: UVA-riboflavin crosslinking can be useful for the treatment of corneal ulceration unresponsive to medical treatment.

Optical Coherence Tomography Angiography Evolution of Choroidal Neovascular Membrane in Choroidal Rupture Managed by Intravitreal Bevacizumab.

PURPOSE: To describe a case of a 25-year-old man with choroidal neovascularization (CNV) secondary to traumatic choroidal rupture treated with intravitreal bevacizumab and to evaluate the vascular structure of the area near the traumatic choroidal rupture. METHODS: The patient underwent complete ophthalmologic evaluation, including best-corrected visual acuity (BCVA), intraocular pressure, anterior segment and funds examination, and optical coherence tomography angiography (OCTA) at baseline and on each follow-up visit. Fluorescein angiography (FA) was performed at baseline. Intravitreal bevacizumab was administered at the time of choroidal neovascular membrane diagnosis. RESULTS: At baseline, ophthalmoscopic examination of the left eye revealed four subretinal macular hemorrhages and two choroidal ruptures located temporally to the fovea. On OCT angiograms, the choroidal rupture appeared as a hypointense break in choriocapillaris plexus. At 4-week follow-up, the OCTA disclosed a well circumscribed lesion characterized by numerous and fine anastomotic vessels. Patient received intravitreal injection of bevacizumab. At 6-week post injection, OCTA documented regression of the neovascular complex. CONCLUSION: Choroidal neovascularization is a common complication associated with traumatic choroidal rupture and OCTA may represent a complementary diagnostic technique to evaluate the vascular structure of the area near the traumatic choroidal rupture.

Panretinal Photocoagulation Does Not Change Macular Perfusion in Eyes With Proliferative Diabetic Retinopathy.

BACKGROUND AND OBJECTIVE: To quantify and compare the vessel density (VD) in the superficial capillary plexus (SCP) and the deep capillary plexus (DCP), as well as the size of the foveal avascular zone (FAZ) in patients with proliferative diabetic retinopathy (PDR) before and after panretinal photocoagulation (PRP). PATIENTS AND METHODS: This prospective clinical study was conducted in the Department of Ophthalmology, Miulli Hospital Acquaviva delle Fonti, Italy. Each patient underwent measurement of best-corrected visual acuity (BCVA), fluorescein angiography, spectral-domain optical coherence tomography (OCT), and OCT angiography (OCTA) at baseline. Patients received PRP within 7 days from baseline, using frequency-doubled Nd:YAG pattern scan laser. BCVA and OCTA were repeated at 1 month and at 6 months. Repeated measure one-way analysis of variance was used to investigate differences between OCTA parameters before and after PRP. RESULTS: Eighteen eyes of 14 patients with diabetes (11 males, 78.6%) were enrolled. Patients underwent a mean of four laser treatments. BCVA was slightly worse at baseline (0.30 ± 0.20) compared to the visual function after 6 months (0.25 ± 0.24; P = .3). FAZ (0.33 ± 0.19 mm2 vs. 0.33 ± 0.16 mm2; P = .6), foveal SCP (16.4 ± 8.0 vs. 16.5 ± 6.5; P = .4), foveal DCP (28.5 ± 8.6 vs. 28.2 ± 8.1; P = .8), parafoveal SCP (38.4 ± 5.7 vs. 38.6 ± 4.5; P = .9), and parafoveal DCP (46.1 ± 5.2 vs. 43.8 ± 5.1; P = .3) did not change 6 months after PRP. CONCLUSIONS: OCTA parameters were not significantly affected by peripheral laser treatment at both short- (1-month) and medium- / long-term (6-month) follow-up. Further analysis with larger samples and longer duration is warranted to confirm these results. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:174-178.].

Osteoporosis-related variations of trabecular bone properties of proximal human humeral heads at different scale lengths.

Osteoporosis (OP) is a skeletal disorder responsible for the weakening of the bone structure and, consequently, for an increased fracture risk in the elderly population. In the past, bone mineral density (BMD) variation was considered the best OP indicator, but recently the focus has shifted toward the variation of microstructural bone parameters. This work is based on the characterisation of 8-mm cylindrical biopsies harvested from proximal humeral heads belonging to healthy and osteoporotic patients, in order to assess the OP-related variations of bone properties at different scale lengths. In particular, bone biopsies underwent micro-computed tomography analysis to study the most relevant features of bone architecture and extrapolate the tissue mineral density (TMD) value of bone trabeculae. Compression tests and nanoindentations were performed to investigate the macro- and micromechanical properties of bone biopsies, respectively. In addition, XRD analyses were performed to obtain the mean hydroxyapatite (HA) crystallite size, while Raman spectroscopy investigated the collagen secondary structure. Thermogravimetric analysis was performed to evaluate the ratio between organic and inorganic phases. From the obtained results, OP samples showed a more anisotropic and less interconnected structure responsible for reduced compression strength. From this, it can be supposed that OP caused an alteration of bone structure that led to inferior macroscopic mechanical properties. Furthermore, OP samples possessed higher TMD and bigger HA crystals that are correlated to an increase of the hardness value obtained by means of nanoindentation. This less controlled HA crystal growth is probably due to an alteration of the organic matrix structure, as revealed by the increase of the random coil contribution in the Raman spectra of the OP bone. This higher crystal content led to an increase in trabecular density and hardness. In conclusion, the obtained data showed that OP affects bone properties at different scale lengths causing an alteration of its morphological, structural and mechanical features.

Characterization of an Additive Manufactured TiAl Alloy-Steel Joint Produced by Electron Beam Welding.

In this work, the characterization of the assembly of a steel shaft into a γ-TiAl part for turbocharger application, obtained using Electron Beam Welding (EBW) technology with a Ni-based filler, was carried out. The Ti-48Al-2Nb-0.7Cr-0.3Si (at %) alloy part was produced by Electron Beam Melting (EBM). This additive manufacturing technology allows the production of a lightweight part with complex shapes. The replacement of Nickel-based superalloys with TiAl alloys in turbocharger automotive applications will lead to an improvement of the engine performance and a substantial reduction in fuel consumption and emission. The welding process allows a promising joint to be obtained, not affecting the TiAl microstructure. Nevertheless, it causes the formation of diffusive layers between the Ni-based filler and both steel and TiAl, with the latter side being characterized by a very complex microstructure, which was fully characterized in this paper by means of Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, and nanoindentation. The diffusive interface has a thickness of about 6 µm, and it is composed of several layers. Specifically, from the TiAl alloy side, we find a layer of Ti3Al followed by Al3NiTi2 and AlNi2Ti. Subsequently Ni becomes more predominant, with a first layer characterized by abundant carbide/boride precipitation, and a second layer characterized by Si-enrichment. Then, the chemical composition of the Ni-based filler is gradually reached.

Optical Coherence Tomography Angiography versus Dye Angiography in Age-Related Macular Degeneration: Sensitivity and Specificity Analysis.

INTRODUCTION: Optical coherence tomography angiography (OCTA) could be a valid tool to detect choroidal neovascularization (CNV) in neovascular age-related macular degeneration (nAMD), allowing the analysis of the type, the morphology, and the extension of CNV in most of the cases. PURPOSE: To determine the sensitivity and specificity of OCTA in detecting CNV secondary to nAMD, compared to fluorescein angiography (FA) and indocyanine green angiography (ICGA). METHODS: Prospective observational study. Patients with suspected nAMD were recruited between May and December 2016. Patients underwent FA, ICGA, spectral domain OCT, and OCTA (AngioVue, Optovue, Inc.). Sensitivity and specificity of FA, with or without ICGA, were assessed and compared with OCTA. RESULTS: Seventy eyes of 70 consecutive patients were included: 32 eyes (45.7%) with type I CNV, 8 eyes (11.4%) with type II CNV, 4 eyes (5.7%) with type III CNV, 6 eyes (8.6%) with mixed type I and type II CNV, and 20 eyes (28.6%) with no CNV. Sensitivity of OCTA was 88% and specificity was 90%. Concordance between FA/ICGA and OCTA was very good (0,91; range 0,81-1,00). CONCLUSIONS: OCTA showed high sensitivity and specificity for detection of CNV. Concordance between OCTA and gold-standard dye-based techniques was excellent. OCTA may represent a first-line noninvasive method for the diagnosis of nAMD.

Corrosion Behavior of Heat-Treated AlSi10Mg Manufactured by Laser Powder Bed Fusion.

This experimental work is aimed at studying the effect of microstructural modifications induced by post-processing heat treatments on the corrosion behavior of silicon-aluminum alloys produced by means of laser powder bed fusion (LPBF). The manufacturing technique leads to microstructures characterized by the presence of melt pools, which are quite different compared to casting alloys. In this study, the behavior of an AlSi10Mg alloy was evaluated by means of intergranular corrosion tests according to ISO 11846 standard on heat-treated samples ranging from 200 to 500 °C as well as on untreated samples. We found that temperatures above 200 °C reduced microhardness of the alloy, and different corrosion morphologies occurred due to the modification of both size and distribution of silicon precipitates. Selective penetrating attacks occurred at melt pool borders. The intergranular corrosion phenomena were less intense for as-produced specimens without heat treatments compared to the heat-treated specimens at 200 and 300 °C. General corrosion morphologies were noticed for specimens heat treated at temperatures exceeding 400 °C.

On the Selective Laser Melting (SLM) of the AlSi10Mg Alloy: Process, Microstructure, and Mechanical Properties.

The aim of this review is to analyze and to summarize the state of the art of the processing of aluminum alloys, and in particular of the AlSi10Mg alloy, obtained by means of the Additive Manufacturing (AM) technique known as Selective Laser Melting (SLM). This process is gaining interest worldwide, thanks to the possibility of obtaining a freeform fabrication coupled with high mechanical properties related to a very fine microstructure. However, SLM is very complex, from a physical point of view, due to the interaction between a concentrated laser source and metallic powders, and to the extremely rapid melting and the subsequent fast solidification. The effects of the main process variables on the properties of the final parts are analyzed in this review: from the starting powder properties, such as shape and powder size distribution, to the main process parameters, such as laser power and speed, layer thickness, and scanning strategy. Furthermore, a detailed overview on the microstructure of the AlSi10Mg material, with the related tensile and fatigue properties of the final SLM parts, in some cases after different heat treatments, is presented.