Production of functionally-graded samples using simultaneous powder and wire-feed

Samples of Ti-6Al-4V containing different volume fractions of TiC have been manufactured using direct laser fabrication. Ti-6Al-4V wire has been fed into the laser at a fixed rate of about 1.1g/min and simultaneously TiC powder has been fed into the molten pool at rates varying from 0.14g/min to 1.03g/min. The rate of powder feed was changed about every 5mm so that samples containing different volume fractions of TiC could be manufactured. Optical microscopy, scanning electron and transmission electron microscopy have been used to characterise the microstructure of these samples. The room temperature tensile properties have also been measured on some selected compositions together with their Young's moduli. In addition the change in wear resistance has been studied as a function of TiC volume fraction using a standard wear test. These observations are discussed in terms of the advantages and difficulties of using simultaneous wire and powder feed systems and in terms of the value of this approach in obtaining data over a wide range of compositions for such a composite.