应变速率对马氏体相变非晶复合材料力学行为的影响

Effect of Strain Rate on Mechanical Behavior of Martensitic Transformation Amorphous Composites

摘要:

金属玻璃具有较高的硬度、高断裂强度和良好的耐腐蚀性能，但室温塑性较差而限制了广泛应用，因此在金属玻璃中引入晶体以提升金属玻璃的力学性能。通过分子动力学模拟研究非晶/晶体双相复合材料，有助于深入理解非晶/晶体双相复合材料的性能和变形机制。采用分子动力学模拟方法研究了不同应变速率对金属玻璃复合材料力学性能的影响，同时在300 K环境温度下对块状B2-CuZr晶体/Cu₅₀Zr₅₀非晶复合材料进行压缩实验。结果表明：随着压缩应变速率增加材料的整体强度提高，与应变速率为2×10⁸s^-1和2×10⁹ s^-1的样品相比，压缩应变速率为2×10¹⁰ s^-1时样品的屈服强度最高达7.8 GPa；随着压缩速率的增加，材料中晶体原子发生相变的数量也增多，样品中块状晶体没有发生明显的偏转，剪切带扩展路径受到阻碍；样品应力应变曲线上出现独特的二次硬化曲线，与另外两种应变速率下样品相比，压缩应变速率为2×10¹⁰ s^-1时样品的强度和塑性均有增加。该研究结果对于设计和制备高性能的金属玻璃材料有参考价值。

Abstract:

Metallic glass has high hardness， high fracture strength and good corrosion resistance， but its poor plasticity at room temperature limits its wide application. Therefore， crystal is introduced into metallic glass to improve the mechanical properties. The study of dual-phase amorphous/crystal composites by molecular dynamics simulation is helpful to understand the properties and deformation mechanisms of dual-phase amorphous/crystal composites in depth. In this paper， the effects of different strain rates on the mechanical properties of metallic glass composites are investigated by molecular dynamics simulation methods. The bulk B2-CuZr crystal/Cu50Zr50 amorphous composites were compressed at 300 K. The results show that the overall strength of the material increases with the increase of compressive strain rate. Compared with the samples with strain rates of 2×108 s^-1 and 2×109 s^-1， the maximum yield strength of the sample with compressive strain rate 2×1010 s^-1 is as high as 7.8 GPa. Moreover， with the increase of the compression rate， the number of crystal atoms undergoing phase transformation also increases， and the massive crystal in the sample does not deflect obviously， and the expansion path of shear band is hindered. A unique secondary hardening curve appears on the stress-strain curve of the sample， which increases the strength and plasticity of the sample compared with the other two strain rates. The results of this paper are useful for the design and preparation of high-performance metallic glass materials.