Mechanical Properties and Damage Tolerance of Bulk Yb3Al5O12 Ceramic

Yb3Al5O12 has potential applications as thermal barrier coatings (TBCs) because it shows low thermal conductivity and close thermal expansion coefficient to nickel-based superalloys. As a prospective TBC material, besides superior thermal properties, the mechanical properties are also important. In this paper, we present the mechanical properties of Yb3Al5O12 including elastic moduli, hardness, strength, and fracture toughness. The Young's modulus of Yb3Al5O12 is 282 GPa. The shear-modulus-to-bulk-modulus ratio of Yb3Al5O12 is 0.63, which indicates relatively low shear deformation resistance. In addition, Yb3Al5O12 exhibits high strength and fracture toughness but low hardness compared to yttria stabilized zirconia (YSZ), the most successful TBC material. SEM observation reveals that the fracture surface of Yb3Al5O12 displays “layered structure feature”, which is caused by crack deflection. Investigation based on Hertzian contact test demonstrates that Yb3Al5O12 is a damage-tolerant ceramic. Crack deflection and bridging can arouse shear faults, dissipate the local damage energy, and restrict the crack propagation within the material, which play an important role in enhancing the damage tolerance. The superior mechanical properties and good damage tolerance ensure Yb3Al5O12 a promising candidate for TBC applications.