Effect of TiB2 addition on the microstructure and wear resistance of Ti-6Al-4V alloy fabricated through direct metal laser sintering (DMLS)

Recent trend in additive manufacturing of Ti-6Al-4V alloy is to alter the microstructure by changing process parameters or by the addition of alloying elements to achieve the required performance. In the present investigation direct metal laser sintering (DMLS) processed Ti-6Al-4V alloy with addition of varying amount of TiB2 has been successfully fabricated. Effect of addition of TiB2 on microstructure, hardness and wear performance was studied using optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), electron back scattered diffraction (EBSD), Vickers micro-hardness and pin-on-disk tribometer respectively. With the increase in addition of TiB2, the microstructure changed from martensite (alpha') lath to refined bimodal structure. Consequently, hardness and wear performance showed dramatic improvement. An elementary hypothesis is proposed for the formation of bimodal structure instead of the martensite structure which is generally observed in DMLS processed Ti-6Al-4V. (C) 2018 Published by Elsevier B.V.