Gomes, Uilame UmbelinoOliveira, Arthur Gabriel Ferreira de2019-11-182019-11-182019-07-26OLIVEIRA, Arthur Gabriel Ferreira de. Obtenção dos compósitos Al203 - 5%Ni e Al203 - 5%Nb utilizando a moagem de alta energia e a sinterização à vácuo. 2019. 97f. Tese (Doutorado em Ciência e Engenharia de Materiais) - Centro de Ciências Exatas e da Terra, Universidade Federal do Rio Grande do Norte, Natal, 2019.https://repositorio.ufrn.br/jspui/handle/123456789/27922Alumina-based cutting tool materials have been extensively studied, particularly with regard to optimizing properties such as fracture toughness, often deficient in these materials. Thus, in this work, the influence of mechanical alloying on the alumina-based composites with nickel or niobium addition was studied using the powder technology route in the material processing. Alumina based composites with 5% nickel addition and 5% niobium were prepared using powders subjected to mechanical mixing and mechanical alloying. Mechanical mixing was performed manually, and the milling was performed in a high energy planetary mill using the times of 5, 10, 20 and 40 hours. The mixed and milled powders were compacted in a uniaxial press using 700 MPa pressure and sintered in a vacuum oven at 1450⁰C for 1 hour. The samples were characterized for their physical and mechanical properties. The microstructure was analyzed by Scanning Electron Microscopy (SEM). Dispersive Energy Spectroscopy (EDAX) with mapping was performed. X-ray diffraction (XRD) with the aid of Xpert software was used to calculate crystallite sizes. The density was obtained by the Archimedes method and the hardness and fracture toughness by the Vickers printing method. The results of the powders processing indicated the gradual reduction of the particle size of the powders with the increase of the surface area, as well as the reduction of the crystallite size and increase of tension in the net. Regarding the consolidation of the powders after sintering, it was observed that increasing the milling time in the preparation of Al2O3 - 5% Ni powders in up to 40 hours, better properties were obtained, among which, density around 96%, hardness 1480 HV and fracture toughness 4,75 MPa.m1/2. For the Al2O3 - 5% Nb composite, the use of powders subjected to 5 hours of high energy grinding already increases the density values to 95.5%, hardness of 1329 HV and fracture toughness of 4,30 MPa.m1/2 .Acesso AbertoAluminaCompósitosMoagem de alta energiaTecnologia dos pósdoctoralThesisCNPQ::ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA