Estudo das transformações de fases ocorridas em ligas de Ti-Nb-Si submetidas a tratamentos termomecânicos

• Ano de defesa: 2019
• Autor(a) principal: Cabral, Helton José Rodrigues
• Orientador(a): Batista, Wilton Walter
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Palavras-chave em Português: Engenharia de materiais; Ligas de titânio; Transformações de fase (Física estatística); Deformação a frio; Recristalização (Metalurgia); Prensagem em canais equiangulares (ECAP)
• Palavras-chave em Inglês: Titanium alloys; Phase transformations; Cold deformation; Recrystallization; Equal Channel Angular Pressing (ECAP)
• Área do conhecimento CNPq: ENGENHARIAS::ENGENHARIA SANITARIA
• Link de acesso: http://ri.ufs.br/jspui/handle/riufs/13138

Ti-Nb-Si alloys have a combination of properties that make them excellent alternatives for use in orthopedic implants. The application of thermomechanical treatments in these materials allows the modification of these properties. This thesis presents a study of the phase transformations occurring in Ti-Nb-Si alloys submitted to thermomechanical treatments. Ti-Nb-Si alloys were produced with three different compositions: Ti-35Nb-XSi (where X = 0.15, 0.25 and 0.35 wt%). After melting, the ingots were homogenized at 1000 ° C for six hours and then deformed by forging at four different levels with the aid of a matrix. Forged alloys were heated at temperatures of 400, 800 and 900 ° C. The alloy with composition of 0.35% Si was also submitted to the deformation process by ECAP. The changes caused by each process were evaluated using optical and scanning electron microscopy, Vickers hardness and X-ray diffraction techniques. The results showed that the cold deformation processes caused the increase of hardness in all the compositions, with the formation of the α-phase. The heating at the different temperatures promoted changes in the microstructura and in the alloys hardness.