Hot forging Nb <sub>4</sub>AlC <sub>3</sub> ceramics with enhanced properties
Ye Yu, Shuai Fu, Detian Wan, Yiwang Bao, Longsheng Chu, Qingguo Feng, Chunfeng Hu
Abstract
Textured Nb<sub>4</sub>AlC<sub>3</sub> ceramics were rapidly and efficiently prepared by hot forging through spark plasma sintering (SPS). The longitudinal compression ratio of textured Nb<sub>4</sub>AlC<sub>3</sub> ceramics was -78.3%, and the lateral expansion ratio was 32.1%. The grains grew preferentially along the direction perpendicular to the <em>c-</em>axis, forming the texture microstructure. The Lotgering orientation factor <em>f</em><sub>(00<em>l</em>) </sub>was calculated to be 0.63. The thermal conductivity of textured Nb<sub>4</sub>AlC<sub>3</sub> ceramics along the <em>c</em>-axis direction (11.23 W·m<sup>-1</sup>·K<sup>-1</sup>) (25 °C) was lower than that of untextured ceramics (13.75 W·m<sup>-1</sup>·K<sup>-1</sup>) (25 °C). The electrical conductivity perpendicular to <em>c</em>-axis direction reached 4.37 × 10<sup>6</sup> S/m at room temperature. The ordered layered grains increased the resistance of crack propagation, resulting in a higher fracture toughness parallel to <em>c-</em>axis direction (9.41 MPa·m<sup>1/2</sup>), which was higher than that of untextured ceramics (6.88 MPa·m<sup>1/2</sup>). The Vickers hardness tested at 10 N on the texture top surface (TTS) (7.18 GPa) was higher than that on the texture side surface (TSS) (6.45 GPa).