Corrosion and wear properties of in situ (TiB+TiC)/TA15 composites with a high volume percentage of reinforcement

The in situ (TiC+TiB)/TA15 composites with different volume percentages of reinforcement (10%, 15%, 20% and 25%) were prepared by water-cooled copper crucible vacuum suspension melting technology. The structures and compositions of the TA15 alloy and its composites were analyzed by XRD and EDS, and their electrochemical corrosion behavior in the 3.5% NaCl solution was studied. Corrosion wear testing was conducted using a reciprocating ball-on-disc wear tester under a 10 N load. Results show that the in situ fibrous TiB phase and the granular TiC phase are uniformly distributed on the composite matrix. The microhardness can reach up to 531 HV as 10vol.% TiC+TiB reinforcement is added. Compared with the TA15 alloy, the volume wear rate decreases from (2.21 & PLUSMN;0.07)x10-4 to (1.75 & PLUSMN;0.07)x10-4 mm3 & BULL;N-1 & BULL;m-1 by adding 15vol.% TiC+TiB reinforcement, and the wear mechanism is adhesive wear. When the volume percentage of the reinforcement phase reaches 25%, the volume wear rate increases from (1.75 & PLUSMN;0.07)x10-4 to (2.41 & PLUSMN;0.07)& BULL;10-4 mm3 & BULL;N-1 & BULL;m-1, and the wear mechanism changes into abrasive wear. The volume loss resulted by the interaction between corrosion and wear accounts for more than 27% of the total wear volume. The volume loss due to wear-induced corrosion changes from 1.94% to 4.06% with different addition of reinforcement. The volume loss caused by corrosion-induced wear initially increases from 24.08% to 26.90% as the reinforcement increases from 0 to 15% due to the increase of corrosion potential, and then decreases from 26.90% to 25.68% as the reinforcement increases from 15% to 25% due to the peeling of TiC phase.