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DEVELOPMENT OF IN SITU BETA TITANIUM METAL MATRIX COMPOSITES FOR HIGH TEMPERATURE APPLICATIONS

Abstract

Recently, the demand for materials with a high ratio between mechanical strength and weight resulted in the more intense use of ²-type titanium alloys. Moreover, the possibility of excellent combinations between toughness, mechanical strength and fatigue justify its use. However, in comparison to ± and ² alloys, it presents low mechanical strength and low modulus of elasticity, and when used at high temperatures, they present excessive grain growth and, consequently, worsen mechanical properties. However, such behavior can be drastically altered by new processing routes, for example by insertion of reinforcing particles into the ² matrix, or more specifically, by the development of titanium metal matrix composites (TMMC). In this new route, we highlight the composites with reinforcements developed via in situ reactions, which, unlike traditional methods, are constituted by the nature of the exothermic transformations involved and/or by recrystallization during the solidification process. For the present proposal, we intend to evaluate the effects of different thermal treatments on the phase transformations and consequently the mechanical properties of metastable ²-matrix composites with Ti-15% Mo and Ti-15% V from B4C additions (0 , 5%, 1.5% and 3.0% by weight). This objective will be achieved by performing the following tasks: (a) preparation of CMMTs via casting, compositional / microstructural homogenization at high temperatures and analysis of the formation of metastable structures resulting from the cooling conditions; (b) evaluation of the effect of different thermal treatments on the microstructure and mechanical properties; (c) evaluation of the ideal conditions to increase the hot working (conformability) due B4C addition, from processing maps design and analysis of fractures and microstructures relative to the stable and unstable regions of these maps. With the development of this research proposal we intend to: 1 - Develop new processing routes and composites with mechanical properties superior to those found in the aerospace industry; 2 - train human resources in the area of processing and characterization of metallic matrix composites, especially titanium; 3 - contribute to the development of technology to obtain, process and characterize alloys/composites for applications in the aerospace industry. Not least, the development of this project will allow the implementation of the materials laboratory and the research-teaching relationship in undergraduate and graduate of School of Applied Sciences. (AU)

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VEICULO: TITULO (DATA)
VEICULO: TITULO (DATA)