Influência da ciclagem térmica nas temperaturas de transformação de fase e quantificação das deformações residuais em ligas com memória de forma cu-al-be-nb-ni

• Ano de defesa: 2012
• Autor(a) principal: Brito., Ieverton Caiandre Andrade
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal da Paraí­ba; BR; Engenharia Mecânica; Programa de Pós Graduação em Engenharia Mecânica; UFPB
• Palavras-chave em Português: Tratamento térmico de têmpera; Transformação de fase; Deformação residual; Superelasticidade; Histerese Térmica; Ciclagem térmica; Envelhecimento; Heat treatment quenching; Phase transformation; Residual deformation; Superelasticity; Thermal Hysteresis; Thermal cycling; Aging; CNPQ::ENGENHARIAS::ENGENHARIA MECANICA
• Link de acesso: https://repositorio.ufpb.br/jspui/handle/tede/5339

In this work was evaluated the influence of multiple quenching in the peak temperatures of phase transformation (PTPT) in the alloy Cu-11.8Al-0.6Be-0.5Nb-0.27Ni (%wt), as well as the influence that deformation applied in temperatures above Ms, at nominal composition Cu-11.8Al-0.6Be-0.5Nb-0.27Ni, Cu-11.8Al-0.55Be-0.5Nb-0.27Ni and Cu-11.8Al-4Nb-2.16Ni-0.5Be, would have on the residual deformation. The alloys were melted, homogenized during 12h by 850ºC and machined using wire electroerosion. Then, the samples were quenched in water at room temperature and subsequently analyzed by optical microscopy, scanning electron microscopy, using energy dispersive x-ray, differential scanning calorimetric analysis and x-ray diffractometry. For samples quenched successively, it was found a large change in PTPT after 22 quenching, there is no reverse transformation in this range. From the 34th quenching, the PTPT remained constant around 420ºC and severe changes in your micrographs were detected. Nevertheless, there was no change in Cu/Al able to change the PTPT. Alloys with containing nominal composition 0.4% and 0.2%Be indicated strong influence of the Be in the PTPT. When analyzed by x-ray diffractometry, the sample with 0.2Be indicated the presence of β' and γ' phases, when aged by 530ºC. For quantifying the residual deformations, the samples were subjected to static tensile and loading/unloading tests. When subjected large deformation and temperature near Ms, the results showed a great residual deformation, whereas small deformations with temperatures above Af showed not to be viable. The alloy Cu-11.8Al-4Nb-2.16Ni-0.5Be when tractioned, showed excessive weakness even after treatment of solubilization.