Effects of plastic working and MA atmosphere on microstructures of recrystallized W-1.1%TiC

Effects of plastic working and the mechanical-alloying atmosphere on microstructures of ultrafine-grained, particle-dispersed W-1.1%TiC compacts, which were developed by powder metallurgical methods, have been investigated by transmission electron microscopy. Plastic working increases the density of the compacts by the reduction of number density of Ar bubbles and pores. Plastic working (PW) enhances the precipitation of TiC at weak grain boundaries of W grains. The precipitated TiC dispersoids have a Kurdjumov-Sachs orientation relationship with the W matrix, thereby significantly strengthening weak grain boundaries of W grains. Such strengthening of weak grain boundaries has not been achieved by hot isostatic pressing irrespective of its temperature. The significant improvement in fracture strength and ductility by PW is primarily due to the strengthening of weak grain boundaries and secondarily due to the decrease in Ar bubbles and pores at grain boundaries. (C) 2011 Elsevier B.V. All rights reserved.