Effect of preparation conditions on phase formation, densification, and microstructure evolution in La-beta-Al2O3/Al2O3 composites

In situ development of La-beta-Al2O3 (LBA) platelets in alpha-Al2O3 was stu died as a function of the preparation method: a conventional solid-state re action of commercial Al2O3 powder and La(NO3)(3) as well as a sol-gel metho d starting with boehmite and the same La2O3 precursor. In both cases, homog eneous distribution of the reinforcing phase was achieved, and a noteworthy inhibition of Al2O3 grain growth resulted. However, samples prepared by so lid-state reaction densified more easily than those prepared via sol-gel, b ut the formation of the LBA phase occurred at a lower temperature in sample s prepared by the sol-gel approach. Results on the correlation of the onset of LBA grain growth and densification to microstructure are discussed.