High temperature microstructural stability and recrystallization mechanisms in 14YWT alloys


Aydogan E. , El-Atwani O., Takajo S., Vogel S. C. , Maloy S. A.

ACTA MATERIALIA, vol.148, pp.467-481, 2018 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 148
  • Publication Date: 2018
  • Doi Number: 10.1016/j.actamat.2018.02.006
  • Title of Journal : ACTA MATERIALIA
  • Page Numbers: pp.467-481
  • Keywords: Nanostructured ferritic alloys, Nano-oxides, Recrystallization, Texture, Neutron diffraction, NANOSTRUCTURED FERRITIC ALLOYS, DISPERSION-STRENGTHENED MATERIALS, GRAIN-BOUNDARY CHARACTERISTICS, TUBE PROCESSING METHODS, SITU HELIUM IMPLANTER, IN-SITU, ORIENTATION RELATIONSHIPS, CRYSTALLOGRAPHIC TEXTURE, IRRADIATION RESPONSE, PLASTIC-DEFORMATION

Abstract

In-situ neutron diffraction experiments were performed on room temperature compressed 14YWT nanostructured ferritic alloys at 1100 degrees C and 1150 degrees C to understand their thermally activated static recrystallization mechanisms. Existence of a high density of Y-Ti-O rich nano-oxides (< 5 nm) shift the recrystallization temperature up due to Zener pinning of the grain boundaries, making these materials attractive for high temperature applications. This study serves to quantify the texture evolution in-situ and understand the effect of particles on the recrystallization mechanisms in 14YWT alloys. We have shown, both experimentally and theoretically, that there is considerable recovery in the 20% compressed sample after 6.5 h annealing at 1100 degrees C while recrystallization occurs within an hour of annealing at 1100 degrees C and 1150 degrees C in the 60% compressed samples. Moreover, the 60% compressed samples show {112} < 110 > and {112}< 111 > texture components during annealing, in contrast to the conventional recrystallization textures in body centered cubic alloys. Furthermore, nano-oxide size, shape, density and distribution are considerably different in unrecrystallized and abnormally grown grains. Transmission electron microscopy analysis shows that oxide particles having a size between 5 and 30 nm play a critical role for recrystallization mechanisms in 14YWT nanostructured ferritic alloys.