Fabrication of Textured Ti₂AlC-MAX Phase Ceramic by Slip Casting under Strong Magnetic Field and Spark Plasma Sintering, and Its Crystal Orientation Dependence of Room Temperature Deformation Behavior

Abstract

The properties of MAX phase ceramics that possess metallic and ceramic nature are anisotropic because of their hexagonal and layered crystal structure. Slip casting under a strong magnetic field followed by spark plasm sintering is one of the methods to control the orientation of the MAX phase ceramics. In this study, first, the textured Ti 2 AlC-MAX phase was fabricated by slip cast under 12 T, where the direction of magnetic field was fixed to the slip cast direction after clarifying the easily magnetizable axis of Ti 2 AlC. Second, the crystal orientation dependence of the room temperature deformation behavior was investigated by the Vickers hardness test from various orientations. It was found that the easily magnetizable axis of Ti 2 AlC was the c-axis and the textured body could be obtained by applying the magnetic field from one direction. In the room temperature deformation, Vickers indents show an anisotropic shape and the hardness changed depending on the loading direction against the c-axis due to different deformation modes such as kink deformation and slip deformation. For 0°, since the slip deformation was unlikely to occur, linear crack growth was observed to form from the indent. For 45°, on the other hand, since the slip deformation occurred relatively easily, the crack growth was suppressed through the stress relaxation due to the slip deformation. For 90°, although the slip deformation is unlikely to occur similar to 0°, the crack propagation was suppressed through pile-up due to kink deformations along the c-axis. It can be concluded that kink deformation prevents crack propagation and increases the fracture toughness of the textured Ti 2 AlC-MAX phase.