Effect of Al Content on Synthesis, Mechanical Properties and Corrosion Resistance of Ti₃(Si,Al)C₂ MAX Solid Solutions

MAX-phase solid solution has attracted much attention for research dealing with complex and harsh working conditions. Solid solutions in a Ti-Al-Si-C system were fabricated from Ti, Si, TiC and Al powders by hot press sintering at 1400 °C for 2 h. Phase identification and micro-morphology were systematically characterized, followed by nano-indentation for mechanical tests and electrochemical tests in NaOH for alkali corrosion tests. The c-lattice parameter increased linearly while the a-parameter was essentially unchanged, which followed Vegard's law and also suggested strong anisotropy of MAX-phase lattices. The addition of Al element caused a solid-solution-strengthening effect, increasing the nano-indentation and elastic modulus. In the electrochemical tests in NaOH solution, with the increased Al content, the corrosion tendency gradually decreased with the increasing charge transfer obstruction, which suggested improved corrosion resistance.