Artículos de revistas
Hexagonal martensite decomposition and phase precipitation in Ti-Cu alloys
Materials & Design. Elsevier Sci Ltd, v. 32, n. 41890, n. 4608, n. 4613, 2011.
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The mechanical behavior of Ti-Cu alloys can be improved by controlling Ti(2)Cu precipitation. In eutectoid alloys, such precipitation can be achieved by the decomposition of martensite in response to aging heat treatment. The purpose of this work is to discuss the evolution of precipitates during the decomposition of hexagonal martensite in Ti-Cu alloys. First, samples with near-eutectoid compositions were prepared in an arc furnace equipped with a non-consumable tungsten electrode and water-cooled copper hearth under a high purity argon atmosphere. After chemical homogenization at a temperature in the beta field, the samples were water-quenched and examined by differential scanning calorimetry and high-temperature X-ray diffraction. The results indicate that rapidly quenched near-eutectoid Ti-Cu alloys present Ti(2)Cu precipitates. Regardless of the cooling rate applied, such precipitation is unavoidable. No evidence of beta phase stabilization was found in the rapidly quenched samples. Precipitation temperatures of coherent and incoherent phases of 415 degrees C and 550 degrees C, respectively, were determined from the differential scanning calorimetry measurements. Ti(2)Cu precipitation was examined in situ by high temperature X-ray diffraction experiments. The total decay of martensite was found to occur above 575 degrees C. Vickers hardness testing of aged samples revealed a correlation between phase precipitation and hardening. (C) 2011 Elsevier Ltd. All rights reserved.324189046084613Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)