ZrO2-Al2O3 eutectic plates produced by laser zone melting

This paper describes a procedure for preparing large surfaces of eutectic c omposites directionally solidified from the melt, with very fine and unifor m microstructures. Large surface plates of the Al2O3-ZrO2 eutectic. with th ickness up to 250 tm, have been grown by solidification using a modified la ser zone melting method suitable for the preparation of large area samples. The surface of a ceramic precursor is scanned with a rectangular CO2 laser beam of 20x0.5 mm(2) size which induces surface melting. The resulting mic rostructure is colony free and it consists of fine and alternating interpen etrating Al2O3 and ZrO2 single crystal lamellae. This microstructure is the basis for improvement of mechanical behaviour in the processed material. T he interspacing, crystal structure and orientation relationship between the phases has been determined. Solidification fronts were studied as a functi on of the processing conditions. A mapping of the residual stresses has als o been performed along the transverse plate sections using micro-luminescen ce techniques. (C) 2001 Elsevier Science Ltd, All rights reserved.