Microstructure characterization of a hydride blister in Zircaloy-4 by EBSD and TEM. (1st May 2017)

• Record Type: Journal Article
• Authors: Long, F.; Kerr, D.; Domizzi, G.; Wang, Q.; Daymond, M.R.
• Is Part Of: Acta materialia. Volume 129(2017)
• Page Start: 450
• Page End: 461
• Publication Date: 2017-05-01
• Subjects: Zirconium -- Hydride -- Orientation relationship -- EBSD -- TEM; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2017.03.016
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: This paper presents a detailed microstructural characterization by EBSD and TEM techniques of a hydride blister grown on a Zircaloy-4 plate. The hydrides formed are found to be of δ-type, and exhibit an increasing volume fraction from alloy matrix, across matrix-blister boundary, and into the blister. The microstructure of the blister mainly consists of δ-hydride platelets, however there is still un-transformed α-Zr phase inside the blister. The orientation relationship between the hydride and alloy matrix has been analyzed. In addition to the commonly observed ( 0001 ) α − Z r / / { 111 } δ orientation relationship, we found hydrides with a secondary ( 0001 ) α − Z r / / ( 100 ) δ orientation relationship. A correlation was drawn between the formation of hydrides with the two orientation relationships and the parent grain orientation. TEM observation revealed the distribution of the remnant α-Zr phase inside the blister, which had either a nodular shape or appeared as thin nano-sized layers among the hydride platelets. The microstructure of the hydrides has been characterized by HRTEM, exhibiting a uniform atomic structure with high dislocation density. Lastly, δ-hydride embryos obeying the primary orientation relationship were found within untransformed α-grains, indicating a consistent nucleation mechanism during blister growth. Graphical abstract: Image