Ti2AlC triggered in-situ ultrafine TiC/Inconel 718 composites: Microstructure and enhanced properties

In situ ultrafine TiC dispersion reinforced Inconel 718 alloy with enhanced mechanical properties was fabricated by the technique of reactive hot-press sintering Ti2AlC and In718 powders. The effect of Ti2AlC precursor additions (5 vol.%, 10 vol.%, 15 vol.%) on microstructure and mechanical properties of TiC/In718 composites were investigated. A relationship of microstructural characteristics, room and elevated temperature mechanical performance, and underlying strengthening mechanisms were analyzed. The results show that initial Ti2AlC precursor transformed completely into ultrafine TiC particulate (similar to 230 nm) and distributed uniformly in the matrix after sintering 5 and 10 vol.% Ti2AlC/In718. However, TiC particulates tended to aggregate to stripes with the addition of Ti2AlC up to 15 vol.%, which, in adverse, weaken the properties of In718. The 5 vol.% Ti2AlC/In718 sample showed a higher tensile strength of 1404 +/- 13 MPa with a noticeable elongation of 9.8% at room temperature compared to the pure In718 (ultimate tensile strength (UTS) = 1310 MPa, elongation = 21.5%). At 600 degrees C, 700 degrees C, 800 degrees C and 900 degrees C, tensile strength of the as-sintered 5 vol.% Ti2AlC/In718 composite was determined to be 1333 +/- 13 MPa, 1010 +/- 10 MPa, 685 +/- 25 MPa and 276 +/- 3 MPa, increased by 9.2%, 14.6%,14.2% and 55%, respectively, compared with that of monolithic In718 alloy. The excellent tensile properties of TiC/In718 composite can be ascribed to the combined mechanisms in term of increased dislocation density, dispersive Orowan and load transfer mechanisms. (C) 2020 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.