Synthesis and characterization of TiB2-Ni-Ni3Al-CrNi alloy graded material by field-activated combustion

The formation of TiB2-Ni/Ni3Al/CrNi alloy functionally graded materials (FGMs) by field-activated combustion synthesis was investigated. Four-layered FGM samples of 50TiB(2)-50Ni(wt%)/30TiB(2)-70Ni/Ni3Al/CrNi alloy were produced in which the intermetallic Ni3Al was reactively formed during the process. Concentration profiles of elements across interfaces between layers showed significant interdiffusion with indication of formation of diffusion bonding. Measured micro-hardness values increased smoothly from the steel substrate to the outer composite layer of 50TiB(2)-50Ni. The values ranged from about 370 to over 3100 HK, over a distance of less than 2 mm. The results demonstrate the feasibility of the field-activated and pressure-assisted combustion synthesis to rapidly form FGMs with good diffusion bonding between the layers. Thermal shock and wear resistance of the FGM were investigated, the wear resistance of the FGM was shown to be higher than the base steel. (C) 2008 Elsevier B.V. All rights reserved.