Microstructure and mechanical properties of Sm1-xSrxCo0.2Fe0.8O3

The room temperature mechanical properties of a mixed conducting perovskite Sm1-xSrxCo0.2Fe0.8O3 (x = 0.2 to 0.8) were examined. Density, crystal phase, and microstructure were characterized. It was found that the grain size increased abruptly with increasing Sr content. Mechanical properties of elastic modulus, microhardness, indentation fracture toughness, and biaxial flexure strength were measured. Young's modulus of 180-193 GPa and shear modulus of 70-75 Cpa were determined. The biaxial flexure strength was found to decrease with increasing Sr content from similar to 70 to similar to 20 MPa. The drop in strength was due to the occurrence of extensive cracking. Indentation toughness showed a similar trend to the strength in that it decreased with increasing Sr content from similar to 1.1 to similar to 0.7 MPa m(1/2). In addition, fractography was used to characterize the fracture behavior in these materials.