Observation of FCC-Zr phase in as-cast Zircaloy-4 alloy

Face-centered cubic (FCC) phase was firstly reported in cold-rolled Zirconium two years ago, and believed to be introduced by sever plastic deformations. The present study introduces the FCC-Zr phase observed in an as-cast Zirconium alloy. The identification of the FCC-Zr phase was carried out using Transmission Kikuchi Diffraction (TKD) as well as TEM methods. It was found that FCC-Zr in the as-cast Zirconium alloy strictly obeyed the orientation relationship with the HCP-Zr matrix: <2110>(hcp)parallel to < 1 1 0 >(fcc), { 0001 }(hcp)-parallel to{1 (1) over bar1}(fcc) . In addition, FCC-Zr phases in the as-cast alloy were preferentially precipitated at grain boundaries, due to the intergranular thermal residual stresses among HCP-Zr grains. (C) 2020 Elsevier B.V. All rights reserved.