Effect of γ'-δ precipitates tailored by Ti3AlC2 on Inconel 718 composites: Microstructure evolution, enhanced properties and strengthening mechanism

The novel Ti3AlC2/Inconel 718 composites were fabricated by in-situ hot press reaction to improve the ther-mostability and strength of the In718 alloy. In this paper, the effect of Ti3AlC2 content on the microstructure and high-temperature properties of composites were investigated. Microstructures and mechanical properties were evaluated using scanning electron microscopy and tensile testing. The phase diagram and time-temperature -transformation curve of & gamma;'-& gamma;"-& delta; phases were simulated by JMatPro6.0 software. The results reveal that Ti3AlC2 has an obvious refining effect on Inconel 718 grain, and the dominant strengthening phase in composites is & gamma;' phase. The tensile results demonstrate that the addition of Ti3AlC2 to the Inconel 718 significantly improves the mechanical properties at elevated temperatures. The 15 vol% Ti3AlC2/Inconel 718 sample showed a higher tensile strength of 1241 & PLUSMN; 13 MPa with a noticeable elongation of 5.2 & PLUSMN; 0.4% at 650 degrees C compared to the pure Inconel 718 (tensile strength = 852 & PLUSMN; 12 MPa, elongation = 7.9 & PLUSMN; 1.1%). At 750 degrees C, 850 degrees C and 900 degrees C, the tensile strength of 15 vol% Ti3AlC2/Inconel 718 composite can reach 911 & PLUSMN; 11 MPa, 459 & PLUSMN; 15 MPa, 283 & PLUSMN; 10 MPa, increased by 35.2%, 61.1% and 68.5%, respectively. The superior strength of the Ti3AlC2/Inconel 718 com-posites is attributed to the dispersive second phases strengthening, grain refinement strengthening, and load transfer strengthening.