Fabrication and Formation Mechanism of B4C–TiB2 Composite by Reactive Spark Plasma Sintering Using Unmilled and Mechanically Activated Reactants

摘要: The fabrication of dense submicrometer grained B4C–TiB2 composite (molar ratio equal to 1:1) is investigated in this work through the combination mechanical (Ball Milling) and electric current (spark plasma sintering or SPS) activation Ti, B, graphite reactants. full conversion 8 h milled powders obtained at much lower temperature (about 1200°C), as compared with simply blended reactants (>1600°C). formation TiB2 generally precedes that B4C. In addition, regardless milling treatment, an increase heating rate during SPS found produce a transition mechanism governing B4C, from gradual solid–solid rapid combustion-type behavior. Nevertheless, when unmilled are used, not negligible amounts unreacted intermediate species still present product resulting after combustion synthesis event. contrast, ball reacted completely under regime, even relatively milder conditions adopted. As consequence density increases about 82% 94% theoretical value (I = 1100 A). Correspondingly, material homogeneous phase distribution grain size down 100–200 nm obtained. regard, regime established, slight coarsening microstructure (1–2 μm) observed. A further improvement (higher than 96.5%) obtained, expenses certain growth, applied intensity augmented 1200 A.