ABSTRACT

The uniaxial flow stress of 1 μm diameter micro-pillars made from single α_Zr grains cut from Zr–2.5%Nb CANDU pressure tube material was assessed in the non-implanted condition and after 6.0 dpa Zr⁺ implantation performed at 25°C and 300°C to simulate neutron irradiation. The normal flow stress, at 10% strain, of the non-implanted micro-pillars was about 70% higher than that for larger diameter polycrystalline pillars indicating length-scale dependence. The flow stress anisotropy displays a stronger length-scale dependence for micro-pillars that were loaded along the <0001> basal pole direction than along other directions. The normalised shear stress of α_Zr micro-pillars aligned for single-slip deformation displayed a dependence upon crystal orientation. These findings provide new information on the mechanisms by which small volume α_Zr phase ligaments, located in crack-tip regions, deform plastically and thus contribute to the ductile fracture toughness of neutron-irradiated Zr–2.5%Nb CANDU pressure tubes.

摘要

在非植入条件下和在 25°C 和 300 下进行6.0 dpa Zr ⁺植入后，评估了由从 Zr–2.5%Nb CANDU 压力管材料切割的单个α _Zr晶粒制成的 1 μm 直径微柱的单轴流应力°C 模拟中子辐照。未植入微柱在 10% 应变下的法向流动应力比较大直径的多晶柱高约 70%，表明长度尺度依赖性。与沿<0001> 基极方向加载的微柱相比，沿<0001> 基极方向加载的微柱的流动应力各向异性显示出更强的长度尺度依赖性。α _Zr的归一化剪应力为单滑变形排列的微柱显示出对晶体取向的依赖性。这些发现提供了关于位于裂纹尖端区域的小体积α _Zr相韧带塑性变形的机制的新信息，从而有助于中子辐照 Zr–2.5% Nb CANDU 压力管的韧性断裂韧性。