Effect of Y₂O₃ and Dy₂O₃ on microstructure and mechanical behaviors of aluminum nitride ceramics

The effects of two types of additives, Y₂O₃ and Dy₂O₃, on the sintering and mechanical behaviors of AlN ceramics were investigated. The experimental results show that the sintering temperature can be decreased and the mechanical behavior can be improved by adding rare earth in AlN ceramics. The strength of AlN ceramics with Y₂O₃ and Dy₂O₃ are 326 and 320 MPa, respectively, which are 97.6% and 93.9% higher than the un-doped AlN ceramics. The fracture behavior on the fracture surfaces of rare earth oxide AlN ceramics was found to be a mixed mode of transgranular fracture and intergranular fracture. As a result, it is concluded that the improvement of bending strength of AlN ceramics with Y₂O₃ and Dy₂O₃ addition are mainly achieved by strengthening the grain boundary.