The shear deformation and fracture behaviors of Zr_xTi_65-xBe_27.5Cu_7.5 metallic glasses (MGs) were systematically investigated in the range x = 20, 25, 30, 35, 40, 45, 50 at% under multi-axial loading mode by small punch test (SPT). Results show that enhanced plasticity can be obtained in MGs with composition ranging from 30 to 45 Zr at%, which is attributed to the large free volume dependent on their better glass forming ability (GFA). It is reasonably concluded that the total free volume consists of two parts: intrinsic free volume ($V_0)$ and excess free volume ($V_G$). Intrinsic free volume, involved in an ideal amorphous structure, is defined as the free volume of MGs undergoing fully structural relaxation, which depends on the atomic size of each element. On the basis of atomic dense packing model, intrinsic free volume of the studied MGs is basically same due to a little difference in the atomic size between Zr and Ti. Excess free volume is crucially dominated by the GFA of MGs. In the case of little difference in atomic size of Zr and Ti, the MGs with large GFA possess a much looser atomic stacking structure, leading to the larger content of excess free volume. The large content of free volume not only favor the better atomic mobility, but also facilitate the nucleation of multiple shear bands, which can dramatically improve the plasticity of MGs. Thus, the studied MGs with Zr content ranging from 30 to 45 at% possess the larger content of total free volume than that with 20, 25 and 50 Zr at% due to their better GFA, depicting the enhanced plasticity induced by the initiation and interaction of multiple shear bands. In addition, the MGs with large content of free volume exhibits the lower driving force of shear bands nucleation, showing a soft state.

 在多轴载荷下，系统地研究了Zr _x Ti _{65- x} Be _27.5 Cu _7.5金属玻璃（MGs）在x = 20、25、30、35、40、45、50 at％范围内的剪切变形和断裂行为。小打孔测试（SPT）模式。结果表明，组成范围为30至45 Zr at％的MG可以获得增强的可塑性，这归因于较大的自由体积，这取决于它们的更好的玻璃成型能力（GFA）。可以合理地得出以下结论：总自由体积由两部分组成：固有自由体积（$V_0）$ 和多余的自由体积（$V_G$）。涉及理想非晶态结构的本征自由体积定义为经历完全结构弛豫的MG的自由体积，这取决于每个元素的原子大小。在原子密集堆积模型的基础上，由于Zr和Ti之间原子尺寸的微小差异，所研究的MG的固有自由体积基本相同。MGs的总建筑面积主要决定了多余的自由体积。在Zr和Ti的原子大小差异不大的情况下，具有较大GFA的MG具有较宽松的原子堆叠结构，从而导致大量的过量自由体积。大量的自由体积不仅有利于更好的原子迁移率，而且还促进了多个剪切带的成核，从而可以显着提高MG的可塑性。从而，Zr含量为30-45 at％的被研究的MG由于具有更好的GFA而具有比20、25和50 Zr at％的MG更大的总自由体积，说明了由多种引发和相互作用诱导的可塑性增强剪切带。另外，具有大量自由体积的MG表现出较低的剪切带形核驱动力，显示出软态。