The nature of the dispersoids in INCONEL alloy M A6000

Abstract

Analytical transmission electron microscopy has been used to examine the oxide dispersion in the mechanically alloyed, nickel-based, dispersion strengthened superalloy INCONEL alloy MA6000. Four mixed AI-Y oxides were identified in consolidated powder: Y3Al5O12, yttrium aluminium garnet (YAG); YAIO3, yttrium aluminium perovskite (YAP); Y4Al2O9, yttrium aluminium monoclinic (YAM), and a previously unidentified YAlOI3 polymorph. This new phase, designated yttrium aluminium hexagonal (YAH), has lattice parameters of a = 2.206 ±0.035 nm and c = 3.219 ± 0.096 nm, a space group of P63mc and consists of 18 closepacked oxygen layers with the yttrium and aluminium cations in the resulting interstices..