Synthesis of Ti matrix composites reinforced with TiC particles: thermodynamic equilibrium and change in microstructure

• Published in: Journal of materials science 2017-04, Vol.52 (7), p.4129-4141
• Main Authors: Roger, Jérôme, Gardiola, Bruno, Andrieux, Jérôme, Viala, Jean-Claude, Dezellus, Olivier
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemical Sciences; Chemistry and Materials Science; Classical Mechanics; Composition; Crystallography and Scattering Methods; Domains; Heat treating; Heat treatment; High temperature; Kurtosis; Material chemistry; Materials Science; Metal matrix composites; Original Paper; Ostwald ripening; Particle size; Particulate composites; Polymer Sciences; Solid Mechanics; Stoichiometry; Thermodynamic equilibrium; Thermodynamics; Titanium carbide
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-016-0677-y

The evolution of TiC reinforcement during the high-temperature consolidation step of a particulate-reinforced Ti matrix composite has been studied. A four-step scenario has been highlighted starting with the dissolution of the smallest particles to reach C saturation of the Ti matrix, followed by a change in the TiC stoichiometry from the initial TiC 0.96 composition to the equilibrium composition (TiC 0.57 ). This change in composition induces an increase in both the total mass fraction of reinforcement and the particle diameter. The diameter increase promotes contact between individual particles in the most reinforced domains and initiates an aggregation phenomenon that is responsible for the observed high growth rate of particles for heat treatment times shorter than 1 h. Finally Ostwald ripening is responsible for the growth of particles for longer heat treatment times.