Densification and mechanical properties of B4C with Al2O3 as a sintering aid

The densification behavior and mechanical properties of B4C hot-pressed at 2000 degreesC for 1 h with additions of Al2O3 up to 10 vol% mere investigat ed, Sinterability was greatly improved by the addition of a small amount of Al2O3. The improvement was attributed to the enhanced mobility of elements through the Al2O3 near the melting temperature or a reaction product forme d at the grain boundaries. As a result of this improvement in the density, mechanical properties, such as hardness, elastic modulus, strength, and fra cture toughness, increased remarkably. However, when the amount of Al2O3 ex ceeded 5 vol%, the level of improvement in the mechanical properties, excep t for fracture toughness, was reduced presumably because of the high therma l mismatch between B4C and Al2O3.