CHARACTERIZATION OF YTTRIUM PHOSPHATE AND A YTTRIUM PHOSPHATE YTTRIUM ALUMINATE LAMINATE

Single-phase yttrium phosphate (YPO4) and a YPO4/ yttrium aluminate (Y3Al5O12) laminate mere studied. Young's modulus, Poisson's ratio, Vickers hardness, and coefficient of thermal expansion of YPO4 sintered bodies were measured, YPO4 and Y3Al5O12 are chemically compatible and morphologically stable up to at least 1600 degrees C. The fracture behavior mas studied by four-point flexural testing on bars with ground or notched tensile surfaces, and by the indentation method. Noncatastrophic fracture could be seen in these specimens, In flexural testing, cracks could be bridged by YPO4 layers, followed by some interfacial debonding, Indentation responses also consistently showed some interfacial delamination in the YPO4/Y3Al5O12 laminate.