Microstructure and fracture toughness of Cr/Cr 2 Nb alloys with trace Y addition

Abstract

The microstructures of binary Cr/Cr₂Nb alloys doped with 0.1 at- rare earth element (REE) Y were characterised by fine interlamellar spacing, and the growth morphology of Cr₂Nb primary phase was transformed from faceted to non-faceted. Moreover, the lamellar spacing was observed to decrease with the decreasing of solidification rate with the addition of REE Y. Furthermore, the mechanical tests showed that the addition of REE Y has a beneficial effect on the room temperature fracture toughness of Cr₂Nb/Cr alloys. The room temperature fracture toughness of the Y doped Cr/Cr₂Nb hypoeutectic and hypereutectic alloys increased by ∼130 and 140 over that of the undoped alloys respectively, which was caused by the refinement of lamellar eutectic and strengthening of lamellar eutectic bonding strength.

Keywords

Laves phase Rare earth element Y Fracture toughness Microstructure

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