弹性应力诱发Zr基非晶合金的结构演化及塑性变形
发布时间：2018-07-22 12:56
【摘要】：块体非晶合金变形是通过高度局域化的剪切带形成及扩展来实现,其特征是塑性变形集中于剪切带内部,合金的脆性与这种不均匀变形行为密切相关,因此非晶合金的塑性与形变过程剪切带的空间增殖密切相关。本文使用循环加载模式,通过控制加载载荷及频率,对Zr52.5Cu179Ni1i4.6Al10Ti5(Vit.105)块体非晶合金试样进行弹性预加载处理。通过研究经预加载处理试样的微观结构演化规律,分析了不同预加载模式对Vit.105块体非晶合金力学性能的影响规律,探讨了合金锯齿流变现象及其与合金剪切带空间增殖能力的关联,主要研究结果如下:预加载处理并不导致Zr52.5Cu179Ni146Al10Ti5块体非晶合金发生晶化,但使其原子结构的空间构型发生变化,发生体积扩张,导致合金自由体积含量增加,如频率的增加引起合金结构弛豫焓变AHr增大,频率增至30Hz时,处理后合金的△Hr增加到-11.3J/g。高载荷预处理导致合金显微硬度下降,如7KN及8KN处理后合金硬度值低于铸态合金,处理后合金的塑性应变值均较铸态合金显著增加,表明循环载荷加载处理提高了合金的塑性性能,6KN、20Hz时合金具有最佳的塑性变形能力。合金断口及侧面形貌表明,频率越高、载荷越大合金内部温升越高;同时侧面剪切带数量有所增加,互相交错阻碍了剪切带扩展。分析预处理试样压缩应力-应变曲线上的锯齿流变行为,发现合金塑性的提高是由于处理后合金内增加的自由体积使剪切带更易形核,同时温升幅度较小的合金内部粘度及温度的回复更快,两者协同进行提高了合金的塑性。
[Abstract]:The deformation of the bulk amorphous alloy is realized by the formation and expansion of the highly localized shear band, which is characterized by the plastic deformation concentrated in the shear zone. The brittleness of the alloy is closely related to this nonuniform deformation behavior. Therefore, the plasticity of the amorphous alloy is closely related to the space proliferation of the shear zone. Zr52.5Cu179Ni1i4.6Al10Ti5 (Vit.105) bulk amorphous alloy specimens were preloaded by elastic preloading by controlling loading load and frequency. The influence of different preloading modes on the mechanical properties of Vit.105 bulk amorphous alloys was analyzed by studying the microstructure evolution of preloaded samples, and the alloy saw tooth was discussed. The main results are as follows: the preloading treatment does not lead to the crystallization of Zr52.5Cu179Ni146Al10Ti5 bulk amorphous alloy, but the spatial configuration of the atomic structure changes and the volume expansion occurs, resulting in the increase of the free volume content of the alloy, such as the increase of frequency. When the alloy structure relaxation enthalpy AHr increases and the frequency increases to 30Hz, the alloy's Delta Hr increases to the -11.3J/g. high load preconditioning leads to the decrease of the alloy microhardness. For example, the hardness of the alloy after 7KN and 8KN treatment is lower than the cast alloy. The plastic strain value of the alloy after treatment is significantly higher than that of the cast alloy, indicating that the cyclic loading treatment is improved. The alloy has the best plastic deformability at 6KN and 20Hz. The alloy fracture and profile show that the higher the frequency and the larger the load, the higher the internal temperature of the alloy, and the increase in the number of the lateral shear bands, which obstruct the expansion of the shear band. It is found that the increase of the plasticity of the alloy is due to the increase of the free volume in the alloy after treatment, which makes the shear band more easy to nucleate, and the internal viscosity and temperature of the alloy with less temperature rise are faster, and the two synergies improve the plasticity of the alloy.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG139.8
本文编号：2137531
[Abstract]:The deformation of the bulk amorphous alloy is realized by the formation and expansion of the highly localized shear band, which is characterized by the plastic deformation concentrated in the shear zone. The brittleness of the alloy is closely related to this nonuniform deformation behavior. Therefore, the plasticity of the amorphous alloy is closely related to the space proliferation of the shear zone. Zr52.5Cu179Ni1i4.6Al10Ti5 (Vit.105) bulk amorphous alloy specimens were preloaded by elastic preloading by controlling loading load and frequency. The influence of different preloading modes on the mechanical properties of Vit.105 bulk amorphous alloys was analyzed by studying the microstructure evolution of preloaded samples, and the alloy saw tooth was discussed. The main results are as follows: the preloading treatment does not lead to the crystallization of Zr52.5Cu179Ni146Al10Ti5 bulk amorphous alloy, but the spatial configuration of the atomic structure changes and the volume expansion occurs, resulting in the increase of the free volume content of the alloy, such as the increase of frequency. When the alloy structure relaxation enthalpy AHr increases and the frequency increases to 30Hz, the alloy's Delta Hr increases to the -11.3J/g. high load preconditioning leads to the decrease of the alloy microhardness. For example, the hardness of the alloy after 7KN and 8KN treatment is lower than the cast alloy. The plastic strain value of the alloy after treatment is significantly higher than that of the cast alloy, indicating that the cyclic loading treatment is improved. The alloy has the best plastic deformability at 6KN and 20Hz. The alloy fracture and profile show that the higher the frequency and the larger the load, the higher the internal temperature of the alloy, and the increase in the number of the lateral shear bands, which obstruct the expansion of the shear band. It is found that the increase of the plasticity of the alloy is due to the increase of the free volume in the alloy after treatment, which makes the shear band more easy to nucleate, and the internal viscosity and temperature of the alloy with less temperature rise are faster, and the two synergies improve the plasticity of the alloy.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG139.8
【参考文献】
相关期刊论文 前3条
1 蒋敏强;;块体金属玻璃的剪切带行为[J];固体力学学报;2012年02期
2 贺林;张帅;孙军;张长军;;Effect of oxygen impurity on long-term thermal stability of Zr-based metallic glasses below glass transition temperature[J];Transactions of Nonferrous Metals Society of China;2006年05期
3 贺林;孙军;;氧对Zr-Cu-Ni-Al-Ti块体非晶合金热稳定性的影响[J];金属学报;2006年02期
，本文编号：2137531
本文链接：https://www.wllwen.com/kejilunwen/jiagonggongyi/2137531.html
