采用XRD, OM, BSE, SEM和显微硬度计等手段研究了氘含量对Zr-4合金显微组织及力学性能的影响. 结果表明, 随着氘含量(质量分数)从1.35%增加到2.21%, 氘化物数量增加, 其形态及分布也发生了显著变化: 在1.35%时, 主要以晶内针状氘化物析出为主; 随着氘含量增加, 晶界块状氘化物快速增长; 当氘含量进一步增加至2.21%时, 晶界块状氘化物开始相互衔接, 并逐渐向晶内生长. 在氘含量较高的样品表层, 有一定厚度的氘化物层形成, 且层内出现微裂纹. 所形成的氘化物以δ-氘化物为主, 而高氘含量样品表面有ε-氘化物出现. 样品心部至表面存在一定的硬度梯度, 且随着氘含量的增加, 样品的硬度增加, 其相应的硬度梯度增大. 随氘含量增加, 样品的屈服强度略有增加, 而抗压强度却显著下降, 由1.35%下的1176 MPa降低到了2.21%下的856 MPa. 抗压强度的降低与组织中微裂纹有关. 样品压缩后的裂纹主要沿晶界块状氘化物形成并扩展, 因此晶界块状氘化物是材料压缩性能下降的主要原因.
Zirconium alloy has been employed widely in nuclear industry, yet the absorption of deuterium in zircaloy is considered to play a critical role in mechanical properties especially in high temperature under a loss of coolant accident (LOCA) and application for deuterium storage. However, little is known about the microstructure evolution of zircaloy during deuterium absorption. In this work, deuterium was charged into the sample at 900oC and different pressures, and the effects of deuterium content on microstructure and mechanical properties of Zr-4 alloy have been studied by means of OM, BSE, SEM, XRD, and hardness and compressive tests. The results showed that the amount of deuteride increased with the increase of deuterium content from 1.35% to 2.21%, accompanying with the morphology variations from intragranular deuteride needles to intergranular deuteride blocks, which formed an interlinked deuteride configuration and grew into equiaxed α-Zr grains. Deuteride layer was observed on the surface of sample at higher deuterium content with the micro-crack appeared within it. The mostly deuteride was δ-deuteride, and ε-deuteride was observed on sample surface with high deuterium content. There existed a hardness gradient from surface to center. With the increase of deuterium content, the hardness increased and hardness gradient became evident. With increasing deuterium content, the compressive yield strength of samples in creased slightly, but the compressive ultimate strength decreased greatly from 1176 MPa (1.35%) to 856 MPa (2.21%). The deceasing of compressive ultimate strength was probably related to the formation of micro-crack. The cracks nucleated and propagated within the intergranular deuteride blocks, which leads to the degradation of compressive ultimate strength.
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