In this research, copper nanocomposites reinforced with carbon nanotubes (CNTs) were produced by ultrasonication and conventional sintering, followed by cold rolling. These nanocomposites may be good candidates due to their excellent properties for components in the electrical, electronics, or aerospace industries with highly demanding requirements. The main objectives of this work were to produce and characterize the Cu/CNT nanocomposites, identify the strengthening mechanisms, and study the deformation behavior of the nanocomposites during cold rolling. The nanocomposites exhibited an improvement in hardness and tensile strength of 17 and 67%, respectively, attesting to the strengthening effect of the reinforced material. The yield strength of the nanocomposites was determined considering different mechanisms: (1) load transfer, (2) grain refinement or texture, (3) dislocation, and (4) Orowan strengthening mechanisms. The microstructural and calculated results show that the mechanism that contributes the most to the increase in the properties of the nanocomposite is the load transfer. The nanocomposites show a different texture evolution of the Cu matrix during cold rolling. This can be due to differences in the active slip planes between the matrix and the nanocomposite, which affects the lattice rotation.

Direct Energy Deposition (DED) is a highly efficient technology for the manufacture and/or repair of different components for multiple industries, including aeronautical. However, a good understanding of the various process variables is essential for producing deposits with the desired properties and ensuring process efficiency. In this study, the optimisation of Inconel 718 single-track deposits was carried out by varying laser power, scanning speed, and powder feed rate to minimise dilution and maximise height, always ensuring the efficiency of the process. The influence of the DED process’ inputs (laser power, scanning speed, and feed rate) and outputs (deposit’s geometry and dilution) were evaluated in the construction of Response Surface Plots and regression analysis equations, allowing the selection of the most promising processing conditions that achieve high-quality single tracks, with predicted dilution percentage, and deposit height. Optimisation analysis selected process parameters, and a block with 300 × 50 × 3 mm³ was built. Mechanical and microstructural characterisation of the built block before and after heat treatment (homogenisation at 1080 °C, followed by solubilisation at 980 °C, and double ageing at 720 and 620 °C) was performed through Optical Microscopy, SEM/EDS analysis, Vickers hardness and tensile tests. It could be observed that the chosen process leads to the formation of a dendritic structure with considerable amounts of Laves phase. However, heat treatments make it possible to obtain a more homogeneous structure with higher amounts of hardening phases, such as γ’ and γ”, which promotes an increase in hardness and tensile strength, and partial elimination of the Laves phase. With proper optimisation of the DED process and understanding of the different parameters’ influence on the deposit’s microstructure, it is possible to manufacture or repair Inconel 718 components for several industries.

Electric vehicles are seen as a key driver to address the issue of global warming, mainly through their zero tailpipe emissions operation and energy efficiency improvements. However, this does not solve the problem of urban chaos, related to traffic congestion and parking space cluttering, which contribute to increase human stress and overall economic productivity decrease. To address all these issues, electric urban buses come as an obvious solution, and they also have the advantages of being quieter than regular buses and of promoting a better travel experience to passengers.Nowadays there are already electric buses operating in some parts of the world and one of the main concerns is their high weight, which is mainly due to the amount of batteries they carry in order to have an adequate range. Several strategies are possible and are being tested to provide buses with adequate operability in terms of range: battery swapping at central stations, battery charging at central stations on slow or fast charge rates and sizing the battery pack to the route of the electric bus using fast charge on bus stops.This paper intends to provide a mathematical model for the electric bus powertrain and its routes, based on a created driving cycle that simulates an acceleration and deceleration period between two stops of a bus. The main objective is to verify how much of the energy recovered from regenerative braking can be absorbed by lithium-ion batteries and to verify whether the supercapacitors can excel the batteries for this purpose. The intent is to reduce the amount of batteries carried, in the attempt to increase the bus efficiency by optimizing regenerative braking capabilities and possibly reduce overall system weight.

Lead (Pb) is widely used in brass alloys (Cu–Zn) to enhance machinability, as its deformation into needle-like particles promotes chip breakage by initiating cracks. However, growing awareness of Pb’s toxicity has led to strict environmental regulations and growing demand for sustainable, lead-free alternatives. This systematic review, conducted following the PRISMA 2020 framework, consolidates recent research on the development and performance of machinable lead-free brass alloys. A comprehensive search was performed in the Web of Science, ScienceDirect, and Scopus databases, identifying 93 studies for full-text analysis. Various strategies have been identified for the development of lead-free brass, including process optimization, heat treatments, direct Pb substitution, and novel alloy design. The review highlights significant progress in achieving acceptable mechanical and machining performance, although trade-offs in cost, corrosion resistance, and large-scale manufacturability remain. The consolidated key findings offer a structured basis for future alloy design and promote consistent evaluation of microstructural, mechanical, and machining properties. Graphical Abstract