Navegando por Palavras-chave "Moagem De Alta Energia"

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    Efeito Do Tempo De Moagem E Do Tratamento Térmico Nas Propriedades Mecânicas De Compósitos De Matriz De Alumínio Aa6061 Reforçados Por Nanotubos De Carbono De Paredes Múltiplas
    (Universidade Federal de São Paulo (UNIFESP), 2018-02-28) Rocha, Geovana Vilas Boas Da [UNIFESP]; Travessa, Dilermando Nagle [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Carbon Nanotubes (Cnt) Are Promising Materials To Strengthen Lightweight Aluminum Matrix Composites, But Their Dispersion Into The Metallic Matrix Is Challenge, Such As The Difficulty Of A Obtaining A Homogeneous Dispersion Of The Cnt Into The Matrix And The Maintenance Of Its Integrity During The Processing Conditions. In The Addition, Addition Of Cnt May Modify The Heat Treatment Cycle. This Study Aimed To Analyze The Influence Of Milling Time And Heat Treatment On The Mechanical Properties Of Aa6061 Aluminum Alloy Matrix Composites Reinforced By Multi Walled Carbon Nanotubes (Mwcnt). The Composites Were Previously Fabricated By Powder Metallurgy Route: Mechanical Alloying (6 And 10 Hours) And Subsequently Hot Extrusion. Mwcnt Are Added Under Different Conditions: Untreated, Functionalized And Functionalized And Decorated With Ag, In 1, 2 And 4% By Weight. Samples Were Also Produced With No Reinforced Addition (Reference Sample) For Comparison Purposes. The Composites Were Analyzed Under The Conditions As E
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    Processamento Das Ligas De Alta Entropia Crcufenizn, Crcufe(Nb)Xnizn (X = 0,5 ; 1) Por Moagem De Alta Energia E Sinterização Spark Plasma
    (Universidade Federal de São Paulo (UNIFESP), 2017-06-21) Bepe, Andre Mello [UNIFESP]; Cardoso, Kátia Regina [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    High-entropy alloys (HEAs) are designed based on selecting elements that will form solid solution phases when combined at near-equiatomic concentrations (5 – 35 at.%). In this study, the selected alloys CrCuFeNiZn, CrCuFeNb0.5NiZn and CrCuFeNbNiZn were processed by hours 40 hours of Mechanical Alloying (M.A) and subsequently consolidated by SPS at 850o C and 50 MPa of uniaxial pressure. The microstructural analysis of both the powder and the sintered alloy samples was carried out using X ray diffractrometry (XRD), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and transmission electron microscopy (TEM). Vickers microhardness testing was conducted to measure the hardness of the produced alloys. The microstructures of the as-milled alloys consist of a disordered face centered cubic (FCC) solid solution phase and a minor percentage of disordered body centered cubic solid solution (BCC) phase. Nb additions were responsible for reducing considerably the crystallite size and inducing partial amorphization in the CrCuFeNb0.5NiZn and CrCuFeNbNiZn alloys. After SPS, both major FCC phase and BCC structures are still present and a new Cu-Ni-Zn rich disordered FCC phase was formed. The formation of the Laves phase (Fe2Nb) in CrCuFeNb0,5NiZn and CrCuFeNbNiZn was observed. Vickers microhardness analysis indicate that the powder samples of CrCuFeNiZn alloy has an average hardness of 533 ± 10 HV while Nb addition further increased the hardness of CrCuFeNb0,5NiZn and CrCuFeNbNiZn alloys to 606 ± 17 HV and 655 ± 18 HV. The sintered alloys present hardness values of 524 ± 9 HV, 602 ± 11 HV, 672 ± 16 HV, respectively. The alloys produced in this study have complex microstructures and high hardness which offers the possibility for them to be a target for future investigations aiming structural applications.