LUIS AUGUSTO MENDES DOS REIS
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Resumo IPEN-doc 29424 Processing of zirconium sponge and zirconium alloys in an electric arc furnace2022 - REIS, L.A.; MORAIS, N.W.; BETINI, E.G.; PEREIRA, L.T.; POLITANO, R.; BARBOSA, L.P.; MARTINEZ, L.G.; MUCSI, C.S.; ROSSI, J.L.Zirconium and its alloys, as well as titanium and its alloys, are mostly used in the nuclear and aeronautical industries, respectively. A nuclear-grade zirconium sponge is the main component for obtaining nuclear fuel element cladding for nuclear power plants and other components, such as grids and springs. The zirconium sponge is also an important raw material in obtaining various alloys for nuclear fuels from small and medium power reactors, such as U-Zr-Nb. Thus, this project has relevance, since the clean melting of zirconium sponge will provide part of the domain of nuclear fuel technology. In this work, high entropy alloys (Ti-Zr-Nb-Ta-Fe-Cr) were produced in order to evaluate the evolution of the microstructure and modulus of elasticity as a function of temperature and heat treatment. A high entropy alloy with a composition different from those found in the literature is proposed. The materials were separated and melted in an electric arc furnace under a non-consumable electrode vacuum. These alloys were consolidated in the form of bars 220 mm long and thicknesses ranging from 8 to 12 mm. After melting, annealing was carried out at 1100 °C for 24 hours to homogenize the material obtained. The initial microstructural analyzes showed two very distinct phases with defined grain boundaries, the chemical etching to reveal the microstructure was a solution of 100 ml deionized H2O + 10 ml HNO3 + 2 ml HF. The samples are being quenched in oil and X-ray diffraction tests will be carried out in a hot chamber and the results will be presented at this congress.Artigo IPEN-doc 27177 On the melting of zirconium alloys from scraps using electron beam and induction furnaces2020 - PEREIRA, LUIZ A.T.; MARTINEZ, LUIS G.; MUCSI, CRISTIANO S.; REIS, LUIS A.M. dos; ROSSI, JESUALDO L.The pressurized water reactor (PWR) employs UO2pellets as nuclear fuel, which are packedin zirconium alloy tubes called nuclear fuel cladding. In the manufacture of the nuclearfuel, machining scraps are generated which are not easily discarded as scraps because ofits high cost. These zirconium nuclear alloys are very costly and are not produced in Brazil.In this work, novel methods to recycle Zircaloy scraps using vacuum induction melting andelectron beam furnaces were used to obtain ingots. The cast ingots were subjected to ther-mal treatments and then chemically analyzed, followed by microstructural characterization,mechanical properties evaluation, and X-ray diffraction. The results indicated the feasibilityof the processes for obtaining alloys for application in the nuclear area, chemical industryor materials for biological applications such as dental prostheses.Artigo IPEN-doc 25828 Study on welding thermal cycle and residual stress of UNS S32304 duplex stainless steel selected as external shield for a transport packaging of Mo-992019 - BETINI, E.G.; GOMES, M.P.; MILAGRE, M.X.; MACHADO, C.S.C.; REIS, L.A.M.; MUCSI, C.S.; ORLANDO, M.T.D.; LUZ, T.S.; MARTINEZ, L.G.; ROSSI, J.L.Thin plates of duplex stainless steel UNS S32304 were welded using the pulsed gas tungsten arc GTAW process (butt joint) without filler addition. The used shielding gas was pure argon and 98% argon plus 2% of nitrogen. The thermal cycles were acquired during welding, in regions near the melting pool. This alloy is candidate for the external clad of a cask for the transport of high activity radiopharmaceuticals substances. For the residual stress measurements in austenite phase an X-ray diffractometer was used in a Bragg-Brentano geometry with CuKα radiation (λ= 0.154 nm) and for ferrite phase was used a pseudo-parallel geometry with CrKα radiation (λ= 0.2291nm). The results of residual stress using sin2 methodology showed that the influence of the high welding temperature leads to compressive stresses for both phases of the duplex steels mainly in the heat-affected zone. It was observed a high temperature peak and an increase of the mean residual stress after addition of ni-trogen to the argon shielding gas.