Tensile strength and microstructure of Al2O3–ZrO2 hypo-eutectic fibers

Al2O3–ZrO2(Y2O3) eutectic materials possess good fracture strengths and creep resistance. Increased Al2O3 content is one means to further improve creep resistance. The objective of this study is to examine fracture strength of Al2O3-rich (hypoeutectic) compositions at varying Y2O3 contents. Fibers 160–220 μm in diameter with 68 m/o Al2O3 and 1.1–7.6 m/o Y2O3 (30.5 to 16 m/o ZrO2) were directionally solidified at 0.11 mm/s using the laser-heated float-zone process. Defect populations increased in size and severity with higher Y2O3 contents. However, fibers maintained 1 GPa fracture strength in the presence of numerous pores and shrinkage cavities, which extend with crack-like morphology along the fiber axis.