Exploring the interfacial state and tensile behaviors in nickel matrix composite with in-situ TiC and γ′-Ni3(Al,Ti) reinforcements

Highlights: • Elaboration of reaction mechanism between Ti₂AlC and Ni contributing to the formation of TiC-γ′/Ni composites. • Characterization of the Ni/TiC and Ni/γ′ interfaces using high resolution electron microscopy. • Evaluation of the tensile property of these novel composites with comparisons to hot-pressed monolithic Ni. This paper presents the study on the formation of a novel nickel matrix composite reinforced with in-situ formed TiC and coherent γ′-Ni₃(Al,Ti) precipitates (TiC-γ′/Ni) processed by reactive hot-press sintering Ti₂AlC and Ni precursors. Detailed interfacial analysis was carried out using high-resolution transmission electron microscopy (HRTEM). Semi-coherent carbide/nickel interface was determined and the orientation relationship between TiC and Ni phases appears to be [001] TiC//[011] FCC Ni and (020) TiC//($\overline{1}1\overline{1}$) Ni. Coherent γ′ -Ni₃(Al,Ti) with ultrafine grain size (less than 100 nm) was separated out from γ-Ni matrix. The fabricated composites exhibits substantially higher yield strength (YS) of 654 ± 38 MPa and 769 ± 44 MPa than monolithic Ni. The great strength enhancement in these composites can be attributed to a refinement grain size led by growth pinning of TiC-γ′ particulates in the nickel matrix coupled with the formation of well-bonded and high-strength TiC/Ni and γ/γ′ interfaces.