Microstructures and properties of porous TiAl-based intermetallics prepared by freeze-casting
(1. State Key Laboratory for Manufacturing Systems Engineering, School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, China;
2. State Key Laboratory of Light Alloy Casting Technology for High-end Equipment, Shenyang Research Institute of Foundry, Shenyang 110022, China;
3. Collaborative Innovation Center for Advanced Aero-Engine, Beijing 100191, China;
4. School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China)
2. State Key Laboratory of Light Alloy Casting Technology for High-end Equipment, Shenyang Research Institute of Foundry, Shenyang 110022, China;
3. Collaborative Innovation Center for Advanced Aero-Engine, Beijing 100191, China;
4. School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China)
Abstract: Preparation of porous TiAl-based intermetallics with aligned and elongated pores by freeze-casting was investigated. Engineering Ti-43Al-9V-1Y powder (D50=50 μm), carboxymethyl cellulose, and guar gum were used to prepare the aqueous-based slurries for freeze-casting. Results showed that the porous TiAl was obtained by using a freezing temperature of -5 °C and the pore structure was tailored by varying the particle content of slurry. The total porosity reduced from 81% to 62% and the aligned pore width dropped from approximately 500 to around 270 μm, with increasing the particle content from 10 to 30 vol.%. Furthermore, the compressive strength along the aligned pores increased from 16 to 120 MPa with the reduction of porosity. The effective thermal conductivities of porous TiAl were lower than 1.81 W/(m·K) and showed anisotropic property with respect to the pore orientation.
Key words: porous TiAl; freeze-casting; pore structures; mechanical properties; thermal conductivity