A new rapid route to in-situ synthesize TiB-Ti system functionally graded materials using spark plasma sintering method

A four-layer TiB-Ti system functionally graded material was rapidly synthesized by spark plasma sintering method using a graphite die with an area-changing cross section. The composition and microstructure of layers in the functionally graded material were characterized by X-ray diffraction and scanning electron microscopy. The mechanical properties of each layer were evaluated using the three-point bending method and the single-edge notched beam method. The results indicate that a stable graded temperature field can be achieved during the SPS process. The in-situ synthesized TiB-Ti system functionally graded material exhibits fine and dense microstructure with continuous and crack free interfaces. The micro-hardness at the layer interfaces is relatively high, suggesting that the interfaces between each layer in the material are well-bonded. The bending strength and the fracture toughness of each layer in the TiB-Ti system functionally graded material synthesized using the pre-designed die are much higher than those of the corresponding layer in the material synthesized using the common cylindrical die. (C) 2012 Elsevier B.V. All rights reserved.