Materials Literature
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Fatigue-crack-growth in an ultrafine-grained (UFG) Al-6%Mg-0.3%Sc alloy is investigated in conjunction with a precise analysis of the fracture surface. The comparison of the crack growth behavior of the UFG and ordinary polycrystalline materials has shown that the fatigue crack growth rate in the UFG alloy is higher t…
Abstract Semi1 and semi2 interpenetrating polymer networks of poly(vinyl chloride) PVC and in situ formed poly(butyl acrylate) (PBA) have been synthesized and characterized using diallyl phthalate (DAP) and ethylene glycol dimethacrylate (EGDM) as the crosslinkers of PVC and PBA, respectively. These two types of IPNs…
Vanadium oxides are a class of materials with outstanding physical and chemical properties. They find a wide field of technological applications such as optical and electrical switching devices, light detectors, temperature sensors, micro batteries, etc. There are several studies regarding the production of vanadium o…
In the present study, fire reaction improvement of an epoxy polymer mortar (PM) formulation, induced by polymer modification with three different flame retardant (FR) systems, was analyzed and quantified. For this purpose, several epoxy PM formulations, modified with different contents and/or types of phosphate, metal…
An ultra-fine grained Al-1.5Mn alloy was fabricated in an oversaturated and a precipitated (Al6Mn particle) state by confined channel-die pressing (CCDP) at room temperature (RT). Specimens for microcharacterization and mechanical tests were taken from the centre area of the CCDP samples, where an equivalent strain of…
This work aimed to prepare biodegradable polymeric materials based on blends of a synthetic high density polyethylene (HDPE) and biodegradable polymers such as polylactic acid (PCL) and poly(caprolactone) (PLA), in a co-rotating twin-screw extruder. A polyethylene modified with maleic anhydride was used as compatibili…
Companies are continuously under pressure to innovate their products and processes. In Portugal, there are already several examples of enterprises that have chosen research groups, associated to universities, to straighten collaboration seeking the development of new materials and advanced technological processes, to…
The interest of the automotive industry on biodegradable and green composites is increasing dramatically due two environmental legislation that obliges automakers to reduce the disposal of waste from vehicles [1]. As an answer to this recent demand several research groups are working on the development of these compos…
The influence of severe thermomechanical treatment via multiple forging on the formation of a nanocrystalline (NC) structure in bulk samples of Alloy 718 and ATI 718Plus has been investigated. It was observed that a step-wise decrease of processing temperature from 950 down to 575°C allowed the refinement of the initi…
Severe plastic deformation of a Mg-Al-Ca alloy resulted in different types of grain structure. High pressure torsion (HPT) was shown to lead to the formation of a nanocrystalline structure with a grain size of 100-200 nm, while equal channel angular pressing (ECAP) produced ultrafine grained (UFG) or submicrocrystalli…
Nanocrystalline metals demonstrate a broad range of fascinating mechanical properties at the nanoscale, namely a significant increase in hardness and superior yield stress. In this regard, understanding grain growth in nanocrystalline metals is crucial, particularly because nano size grains are characterized by a high…
A numerical model was developed which enables the calculation of the optical constants (refractive index, n and extinction coefficient, k) of thermochromic coatings based in undoped and doped vanadium dioxide thin coatings deposited on glass for use as an intelligent window - a window that can change the optical prope…
Prepared were p-type Bi2Te3-based thermoelectric semiconductors, having a grain-refined microstructure and a preferred orientation of anisotropic crystallographic structure. Disks with a nominal composition Bi0.5Sb1.5Te3.0 were cut from an ingot grown by the vertical Bridgman method (VBM) and deformed at 473 K under a…
Abstract Blends of poly(ethylene terephthalate) (PET) and poly(ethylene naphthalate) (PEN) were processed into biaxially drawn films, and samples taken from the bi‐oriented films were then investigated by dynamic rheology experiments in the melt state. Storage modulus G′ and loss modulus G″ were determined in the freq…
The sustainable world’s economic growth and people’s life improvement greatly depend on the use of alternative products in the architecture and construction, such as industrial wastes conventionally called “green materials”. This paper concerns the main results of an experimental work carried out with the objective of…
The microstructure evolution during high pressure torsion and its influence on the mechanical properties of AZ80 magnesium alloy is presented in this study. Significant grain refinement was observed after high pressure torsion, while the homogeneity of the grain structure increases with the number of revolutions. Grai…
Industrial available FeSi, FeCo and FeNi alloys with an initial grain size of 20-50 m were subjected to Severe Plastic Deformation (SPD) up to strain levels where a saturation of the microstructural refinement is observed. For both SPD conditions, ambient temperature (293 K) and liquid nitrogen temperature (77 K), the…
Microstructural evolution taking place during equal channel angular pressing (ECAP) was studied in a commercial coarse-grained Al-6%Mg-0.4%Mn-0.3%Sc alloy in a temperature interval 200- 450oC (~0.5-0.8 Tm). Samples were pressed using route A to a total strain of 12 and quenched in water after each ECAP pass. Uniform f…
Technical purity Cu (99.95 wt%) polycrystals have been processed at room temperature by equal channel angular pressing. The results of mechanical tests and the microstructure characterization by various experimental techniques are presented. The yield stress as well as the strength were shown to increase with increasi…
Bulk nanostructured Cu samples with 20 mm in diameter and 1 mm in height were processed by HPT at a pressure of 6 GPa by 10 rotations. Measurements of texture by means of state-of-the-art XRD technique have been achieved in directions parallel and normal to the torsion axis. Local texture measurements were performed b…