钨在不同损伤程度氦离子辐照后的力学性能变化

Mechanical Property Changes of Tungsten after Helium Ion Irradiation with Different Damage Degree

采用不同能量和束流的氦离子对再结晶钨表面进行辐照试验,对辐照损伤分别为0.2,0.5,1.0 dpa下钨的微观形貌进行观察,并采用不同半径(1,5,10μm)球形压头对其进行纳米压痕试验,获得压痕应力-应变曲线,探究其力学性能的变化及原因。结果表明:不同损伤程度辐照后钨表面损伤层的厚度为554~558 nm;随着辐照损伤程度的加剧,钨中位错环密度明显增大;辐照后钨的压痕应力-应变曲线均未出现突跳现象,且随着辐照损伤程度的增加,屈服强度提高,压痕弹性模量基本保持不变,辐照后产生的位错环缺陷是引起钨力学性能发生变化的直接原因;钨的力学性能具有压痕尺寸效应,压头半径越小,钨的屈服强度越高,未辐照钨的压痕应力-应变曲线出现突跳现象时的压痕应力越大。

The surface of recrystallized tungsten was irradiated by helium ions with different energy and ion fluence. The microstructure of tungsten with irradiation damage of 0.2,0.5,1.0 dpa was observed. The nanoindentation test was conducted with spherical indenter of different radius(1,5,10 μm) to obtain the indentation stress-strain curve, and the change of mechanical properties and reason for the change were explored. The results show that the thickness of damage layer on tungsten surface was 554-558 nm after irradiation with different damage degree. With increasing damage degree, the density of dislocation loop in tungsten increased obviously. The indentation stress-strain curves of tungsten after irradiation did not exhibit pop-in phenomenon, and the yield strength increased with damage degree, and the indentation elastic modulus basically unchanged. The dislocation loop defect caused by irradiation was the direct cause of the change of mechanical properties of tungsten. The mechanical properties of tungsten had the effect of indentation size. The smaller the indenter radius, the higher the yield strength of tungsten, and the greater the indentation stress when the stress-strain curve of unirradiated tungsten showed pop-in.