Effects of He ion irradiation on the structural stability and deformation behavior in Zr63.5Cu23Al9Fe4.5 and Fe80B13Si7 metallic glasses

The effects of He2+ irradiation on the structural stability and deformation behavior in Zr63.5Cu23Al9Fe4.5 and Fe80B13Si7 metallic glasses (MGs) were investigated by TEM and nano-indenter. He bubbles in Fe80B13Si7 MG distributed more narrowly along the depth direction, packed more densely and exhibited larger size. At 4 × 1017/cm2 dose, Fe3B nanocrystals generated in Fe80B13Si7 MG caused by enhanced atomic diffusion due to increased excess free volume and larger compressive stress on atoms of bubbles gaps, while Zr63.5Cu23Al9Fe4.5 MG could maintain the amorphous structure. According to serrated flow phenomenon and bubbles distribution, the underlying mechanism of the transformation in deformation behavior of MGs with increasing He dose was analyzed as follows: localized inhomogeneous deformation in as-cast MGs, homogeneous deformation in the rejuvenated stage, localized inhomogeneous deformation in the stage where small bubbles act as weak pinning, homogeneous deformation in the stage where large bubbles act as strong pinning, localized fracture in the stage where bubbles collapse.