Deformation twinning in zircaloy 2

Abstract

Fully recrystallised zircaloy 2 samples were subjected to different degrees of uniaxial compression. Grains of high Taylor factors showed {1012}〈1011〉 deformation twins, noticeable up to 13–16% compression. Twinning strongly affected the crystallographic texture and also brought in clear differences in stored energy and residual stress between the suspected parent and product grains/orientations of twinning. At later stages of deformation, where presence of twinning was insignificant, aforementioned heterogeneity was further supplemented by heterogeneity in microstructure – clear presence of fragmenting and non-fragmenting grains. Direct observations on twin fraction, twin deviation and twin continuity had shown an apparent peak in twinning by ∼7·5% compression, an observation explainable through a simple model of twin decay by in grain misorientation development.

Deformation Twinning in Zirconium: Direct Experimental Observations and Polycrystal Plasticity Predictions

“…It needs to be noted, that appropriate specimen surfaces were subjected to standard metallography and electro-polishing. [12] For the latter, a Struers TM Tenupol-5 system was used with 20:80 perchloric acid: methanol by volume, À20°C and 20 volts dc.…”

“…[12], thus, does not explicitly account for the granular neighborhood of g: Nevertheless, writing out Eq. [12] for any pair of grains g 1 and g 2; and subtracting them from each other yields…”

“…[12], angle brackets denote averaging over all grains. These average strain-rate and stress fields correspond to the homogeneous effective medium.…”

“…Deformation twinning can have a significant effect on microstructural development and mechanical behavior. [10,[12][13][14][15][16][17] This has important consequences in the context of zirconium alloy components, whose fabrication and inreactor usage are associated with inelastic deformation. [18,19] Material purity, microstructure, texture, processing temperature, strain mode, and strain-rate are wellestablished parameters that influence deformation twinning in pure zirconium and zirconium alloys.…”

Encruamento, recristalização e textura cristalográfica de zircônio puro e da liga Zircaloy-4.

“…Sua presença é verificada em zircônio e ligas, mas há controvérsias com relação à sua importância na deformação deste metal em específico. Sahoo [72] Figura 16: Sistemas de maclação em zircônio alfa [61].…”