Insights into strengthening behavior of two-dimensional nanosheets in titanium matrix composites involving a novel MXene/Ti composite powder

The intrinsic strengthening behavior and underlying mechanism of two-dimensional (2D) reinforcement in titanium matrix composites (TMCs) continues to be a subject of interest because traditional nanosheets, such as graphene and reduced graphene oxide, either agglomerate or severe interfacial reaction occurs with the Ti matrix. In contrast, 2D transition-metal carbides and nitrides (known as MXene) have superior chemical inertness with Ti compared to graphene, enabling us to remain the original structure for studying the strengthening mechanism of 2D nanosheets in TMCs. Thus, a novel Ti3C2 MXene-coated Ti composite powder was developed in this study through surface functional modification of MXene followed by powder coating using fluidized bed. After sintering, the MXene remained in the Ti matrix and exhibited the desired synergy of uniform dispersion characteristics and unique monolayer structure, which enabled it to have a distinctive strengthening behavior and significant effect on enhancing the tensile properties and hardness of Ti matrix. The addition of 0.2 wt% MXene increased the yield strength of sample from 435 ± 13 to 710 ± 21 MPa, while remaining an acceptable ductility (a tensile elongation of 12.5 ± 1.2%). The strengthening efficiency of MXene reached ∼60%, which was superior compared to the majority of reported data for traditional 2D reinforcements in TMCs. New insights into the strengthening behavior and the underlying mechanism of 2D reinforcements obtained as a consequence of the strengthening behavior of uniformly dispersed and monolayer MXene nanosheets in TMCs are presented and discussed.