gamma ' precipitates with a twin orientation relationship to their hosting grain in a gamma-gamma ' nickel-based superalloy

摘要

In a polycrystalline gamma-gamma' nickel-based superalloy, gamma' precipitates with a close-to-twin orientation relationship to their surrounding matrix (named T-type precipitates) are found in recrystallized grains located near specific unrecrystallized grains (named recovered grains). This type of gamma/gamma' interface has not been reported in literature before. Inherited from the ingot conversion process, recovered grains are characterized by a high density of micrometric and close-to-coherent gamma' precipitates. Resulting from the interaction of the recrystallization front with the latter precipitates, the T-type precipitates appear to form onto the recrystallization front. The present paper details the crystallographic characteristics of the T-type precipitates. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.