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 phas e, and microstructure were characterized. It was found that the grain size increased abruptly with increasing Sr content. Mechanical properties of ela stic modulus, microhardness, indentation fracture toughness, and biaxial fl exure strength were measured. Young's modulus of 180-193 GPa and shear modu lus 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 MP a. The drop in strength was due to the occurrence of extensive cracking. In dentation toughness showed a similar trend to the strength in that it decre ased 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 beha vior in these materials.