Microstructure and Mechanical Properties of Alumina Composites with Addition of Structurally Modified 2D TiC (MXene) Phase.

This study presents new findings related to the incorporation of MXene phases into ceramic. Aluminium oxide and synthesised TiC were utilised as starting materials. Knowing the tendency of MXenes to oxidation and degradation, particularly at higher temperatures, structural modifications were proposed. They consisted of creating the metallic layer on the TiC, by sputtering the titanium or molybdenum. To prepare the composites, powder metallurgy and spark plasma sintering (SPS) techniques were adopted. In order to evaluate the effectiveness of the applied modifications, the emphasis of the research was placed on microstructural analysis. In addition, the mechanical properties of the obtained sinters were examined. Observations revealed significant changes in the MXenes degradation process, from porous areas with TiC particles (for unmodified TiC), to in situ creation of graphitic carbon (in the case of TiC-Ti/Mo). Moreover, the fracture changed from purely intergranular to cracking with high participation of transgranular mode, analogously. In addition, the results obtained showed an improvement in the mechanical properties for composites with Ti/Mo modifications (an increase of 10% and 15% in hardness and fracture toughness respectively, for specimens with 0.5 wt.% TiC-Mo). For unmodified TiC, enormously cracked areas with spatters emerged during tests, making the measurements impossible to perform.