Unexpected dynamic transformation from phase to phase in zirconium alloy revealed by in-situ neutron diffraction during high temperature deformation

高温変形中のその場中性子回折から明らかになったジルコニウム合金の相から相への予期せぬ動的変態

Guo, B.*; Mao, W.; Chong, Y.*; 柴田 曉伸*; Harjo, S.   ; Gong, W.   ; Chen, H.*; Jonas, J. J.*; 辻 伸泰*

Guo, B.*; Mao, W.; Chong, Y.*; Shibata, Akinobu*; Harjo, S.; Gong, W.; Chen, H.*; Jonas, J. J.*; Tsuji, Nobuhiro*

Dynamic transformation from alpha (HCP) to beta (BCC) phase in a zirconium alloy was revealed by the use of in-situ neutron diffraction during hot compression. The dynamic transformation was unexpectedly detected during isothermal compression at temperatures of 900C and 950C (alpha + beta two-phase region) and strain rates of 0.01 s and 0.001 s, even though equilibrium two-phase states were achieved prior to the hot compression. Dynamic transformation was accompanied by diffusion of Sn from beta to alpha phase, which resulted in changes of lattice parameters and a characteristic microstructure of alpha grains. The details of dynamic transformation are discussed using the evolution of lattice constants.