Additive manufacturing, a highly promising and impactful manufacturing process, is experiencing increasing adoption across numerous industrial sectors, especially in industries that utilize metallic components. It allows for the creation of complex parts with reduced waste, leading to the production of lighter structures. A thoughtful approach to technique selection in additive manufacturing is imperative, depending on the chemical profile of the material and the desired final product specifications. The technical development and mechanical characteristics of the final components receive considerable scrutiny, but their corrosion performance across diverse operating conditions is relatively neglected. This paper's objective is a thorough examination of how the chemical makeup of various metallic alloys, additive manufacturing procedures, and their subsequent corrosion resistance interact. It aims to pinpoint the influence of key microstructural elements and flaws, including grain size, segregation, and porosity, which stem from these particular processes. Additive manufacturing (AM) systems, including aluminum alloys, titanium alloys, and duplex stainless steels, are evaluated for their corrosion resistance, providing a knowledge base from which novel ideas in materials manufacturing can be derived. To improve corrosion testing practices, some conclusions and future recommendations are provided.
In the preparation of metakaolin-ground granulated blast furnace slag geopolymer repair mortars, several factors bear influence: the MK-GGBS ratio, the solution's alkalinity, the alkali activator's modulus, and the water-to-solid ratio. learn more Interactions between these components are evident in differing alkaline and modulus demands of MK and GGBS materials, the relationship between alkali activator solution alkalinity and modulus, and the continuing presence of water throughout the entire procedure. Full comprehension of how these interactions impact the geopolymer repair mortar is essential to the optimization of the MK-GGBS repair mortar ratio; currently, this understanding is limited. learn more Response surface methodology (RSM) was employed in this paper to optimize repair mortar preparation, focusing on the key factors of GGBS content, SiO2/Na2O molar ratio, Na2O/binder ratio, and water/binder ratio. Evaluation of the optimized mortar was carried out by assessing 1-day compressive strength, 1-day flexural strength, and 1-day bond strength. An analysis of the repair mortar's overall performance included examination of factors such as setting time, long-term compressive and adhesive strength, shrinkage, water absorption, and the development of efflorescence. The application of RSM successfully demonstrated a link between the repair mortar's properties and the factors. The suggested values for GGBS content, Na2O/binder ratio, SiO2/Na2O molar ratio, and water/binder ratio are, respectively, 60%, 101%, 119, and 0.41. The optimized mortar's performance regarding set time, water absorption, shrinkage values, and mechanical strength conforms to the standards with minimal efflorescence. BSE images and EDS data highlight strong interfacial adhesion of the geopolymer to the cement, exhibiting a denser interfacial transition zone in the optimally proportioned mix.
Traditional InGaN quantum dot (QD) synthesis processes, including Stranski-Krastanov growth, often yield QD ensembles with a low density and a non-uniform size distribution. Photoelectrochemical (PEC) etching with coherent light has been implemented to create QDs, thereby overcoming these challenges. This investigation demonstrates the anisotropic etching of InGaN thin films, facilitated by PEC etching. A 100 mW/cm2 average power density pulsed 445 nm laser is used to expose InGaN films that have been etched in dilute H2SO4. Varying potentials of 0.4 V or 0.9 V, referenced to an AgCl/Ag electrode, were employed during PEC etching, thereby producing unique quantum dots. Images from the atomic force microscope show that, for the applied potentials examined, while the quantum dot density and size parameters remain similar, the uniformity of the dot heights aligns with the original InGaN thickness at the lower potential. Polarization-induced fields, as revealed by Schrodinger-Poisson simulations, hinder the arrival of positively charged carriers (holes) at the c-plane surface within the thin InGaN layer. These fields' impact is lessened in the less polar planes, resulting in a high degree of selectivity during etching for the distinct planes. Exceeding the polarization fields, the amplified potential disrupts the anisotropic etching.
In this paper, the cyclic ratchetting plasticity of nickel-based alloy IN100 is investigated via strain-controlled experiments, spanning a temperature range from 300°C to 1050°C. The methodology involves the performance of uniaxial material tests with intricate loading histories designed to elicit various phenomena, including strain rate dependency, stress relaxation, the Bauschinger effect, cyclic hardening and softening, ratchetting, and recovery from hardening. Plasticity models, characterized by varying degrees of sophistication, are described, accounting for these phenomena. A strategy is presented for the determination of the numerous temperature-dependent material properties of these models through a step-by-step process, utilizing selected subsets of experimental data gathered during isothermal tests. Non-isothermal experiments' results are used to validate the models and their corresponding material properties. A description of the time- and temperature-dependent cyclic ratchetting plasticity of IN100, encompassing both isothermal and non-isothermal loading, is provided. Models integrating ratchetting terms within their kinematic hardening laws and material properties determined using the proposed strategy are employed.
The issues surrounding the control and quality assurance of high-strength railway rail joints are presented in this article. Based on the stipulations within PN-EN standards, a detailed account of selected test results and requirements for rail joints created via stationary welding is provided. Destructive and non-destructive weld testing procedures were implemented, encompassing visual assessments, precise dimensional measurements of imperfections, magnetic particle and penetrant tests, fracture tests, microscopic and macroscopic analyses, and hardness measurements. The extent of these examinations extended to conducting tests, diligently overseeing the procedure, and appraising the obtained results. The rail joints' quality, originating from the welding shop, was meticulously evaluated through laboratory testing. learn more Evidence of diminished track damage at newly welded sections validates the efficacy of the laboratory qualification testing procedure. The presented study will inform engineers on the intricacies of welding mechanisms and the imperative of quality control measures within their rail joint design considerations. The findings of this research are indispensable to public safety and provide a critical understanding of the correct application of rail joints and the execution of quality control measures, adhering to current standard requirements. To minimize crack formation and select the suitable welding procedure, these insights will aid engineers in their decision-making process.
Composite interfacial properties, including interfacial bonding strength, interfacial microelectronic structure, and related parameters, are hard to assess accurately and quantitatively via conventional experimental procedures. Conducting theoretical research is essential for guiding the regulation of interfaces in Fe/MCs composites. A systematic first-principles computational study of interface bonding work is presented herein; however, this analysis disregards dislocations to simplify model calculations. The interfacial bonding characteristics and electronic properties of -Fe- and NaCl-type transition metal carbides, specifically Niobium Carbide (NbC) and Tantalum Carbide (TaC), are scrutinized. Interface energy is determined by the bond strengths of interface Fe, C, and metal M atoms, manifesting as a lower Fe/TaC interface energy compared to Fe/NbC. Measurements of the composite interface system's bonding strength are performed with precision, and the strengthening mechanism at the interface is examined from atomic bonding and electronic structure viewpoints, ultimately furnishing a scientific basis for controlling the interface architecture of composite materials.
This paper optimizes a hot processing map for the Al-100Zn-30Mg-28Cu alloy, accounting for strengthening effects, primarily focusing on the crushing and dissolution of its insoluble phases. Compression testing of hot deformation experiments involved strain rates varying from 0.001 to 1 s⁻¹ and temperature fluctuations from 380 to 460 °C. The hot processing map was constructed using a strain of 0.9. The optimal hot processing temperature range lies between 431°C and 456°C, with a strain rate falling between 0.0004 s⁻¹ and 0.0108 s⁻¹. The real-time EBSD-EDS detection technology was used to demonstrate the recrystallization mechanisms and the evolution of the insoluble phase in this alloy. By raising the strain rate from 0.001 to 0.1 s⁻¹ and refining the coarse insoluble phase, the effects of work hardening are lessened. This process enhances existing recovery and recrystallization techniques. However, the impact of insoluble phase crushing on work hardening decreases for strain rates greater than 0.1 s⁻¹. Refinement of the insoluble phase was optimal at a strain rate of 0.1 s⁻¹, which facilitated sufficient dissolution during the solid solution treatment, leading to excellent aging strengthening effects. The hot working region was further optimized in the final step, resulting in a strain rate of 0.1 s⁻¹ in place of the prior 0.0004 to 0.108 s⁻¹ range. The offered theoretical framework is a crucial component in understanding the subsequent deformation of the Al-100Zn-30Mg-28Cu alloy and its application to aerospace, defense, and military engineering.