Structural rejuvenation and relaxation of a metallic glass under the periodically thermal-mechanical loading

Liang, S.Y.; Zhang, L.T.; Wang, B.; Wang, Y.J.; Pineda, E.; Qiao, J.C.

doi:10.1016/j.intermet.2023.108115

Cited by 12 publications

(5 citation statements)

References 64 publications

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“…恒定应变条件下, 材料在变形过程中应力随时间变化而逐渐减小的现象, 本质上应力弛豫行为与蠕变过程相同. 此外, 应力弛豫行为是黏弹性材料具备的典型特性之一, 已经被证明是定量研究玻璃态材料与时间相关结构弛豫等现象的有效手段之一 [30][31][32][33][34][35] .…”

Section: 应力弛豫(Stress Relaxation)是指给定温度和unclassified

“…积模型 [55][56][57] , 对非晶体系施加外力或加热时, 体系内会发生一定程度的原子迁移运动, 自由体积降低. 根据应力弛豫的热活化理论, 激活体积可以推导为 [34,58,59] 快过程与慢过程. Luo等 [36,37] 对 Zr 应力驱动的快过程几乎是瞬时的短程原子重排运动, 而热激活的慢过程则是快过程的渗流, 由长程原子扩散所容纳 [34] .…”

Section: 进一步对应力弛豫结果进行分析根据自由体unclassified

“…根据应力弛豫的热活化理论, 激活体积可以推导为 [34,58,59] 快过程与慢过程. Luo等 [36,37] 对 Zr 应力驱动的快过程几乎是瞬时的短程原子重排运动, 而热激活的慢过程则是快过程的渗流, 由长程原子扩散所容纳 [34] . 低温时, 条带样品的激活体积大于块体样品, 随温度升高, 两者结构状态趋同, 变形一致.…”

Section: 进一步对应力弛豫结果进行分析根据自由体unclassified

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Effects of cooling rate on β relaxation process and stress relaxation of La-based amorphous alloys

Meng,

Hao,

Wang

et al. 2024

Acta Phys. Sin.

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The dynamic relaxation process and stress relaxation are important experimental methods to reflect the microstructure of materials, which are closely related to the diffusion, the glass transition phenomenon and the microstructural heterogeneity. It is of great significance to explore the relationship between them. In the current research, the β-relaxation characteristics and stress relaxation behaviors of bulk and ribbon samples obtained by different cooling rates are systematically investigated using the typical La-based amorphous alloys as model systems. The experimental results demonstrated that the cooling rate is an important parameter for controlling the energy state of the glass system, which in turn affects its physical and mechanical properties. Based on the dynamical mechanical spectra, the larger the cooling rate, the greater the low-temperature internal friction, the smaller the beta relaxation activation energy according to Arrhenius calculations, and the greater the broadening of the beta relaxation behavior in the temperature spectra, suggesting that the higher cooling rate leads to greater atomic mobility and a high degree of heterogeneity in the microstructure. Thermodynamic analysis is used to study the slow process of thermal activation and the fast process driven by stress. At low temperature, the activation volume of the strip sample is larger than that of the bulk sample, and the activation volume value of the two samples is almost the same as that of the cooling rate only affects the β relaxation stage, but has little effect on the α relaxation, which is consistent with the conclusion that the stress relaxation and β relaxation behavior are related to the structural non-uniformity of the amorphous alloy. Based on stress relaxation tests, the characteristic time of deformation decreases at higher cooling rates, the normalized stress decay is larger, it is easier to deform under an applied force field, and the deformation units are more likely to activate to accommodate structural deformation. The correlation between stress relaxation and β relaxation of amorphous alloys is further confirmed, and the proportion of liquid-like region is proportional to the relaxation mode spectrum, which also shows that β relaxation and stress relaxation are consistent. Finally, by calculating relaxation enthalpy △Hrel, the variation of microstructure heterogeneity with cooling rate is experimentally verified. The research sheds new light on further clarifying the association between β relaxation, deformation and microstructural heterogeneity of the amorphous alloy.

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Section: 应力弛豫(Stress Relaxation)是指给定温度和unclassified

Section: 进一步对应力弛豫结果进行分析根据自由体unclassified

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Effects of cooling rate on β relaxation process and stress relaxation of La-based amorphous alloys

Meng,

Hao,

Wang

et al. 2024

Acta Phys. Sin.

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“…对于低温段β弛豫行为, 在不同玻璃体系中表现出不同形式. 通常, La基体系表现为明显的β弛豫峰(peak), Pd基体系表现为肩膀峰(shoulder), CuZr基非晶合金β弛豫难以被直接观测而表现为α弛豫的过剩尾(excess wing) [14,25,26] . 的力学行为 [21] .…”

Section: 玻璃形成熔体在冷却过程中其动态弛豫行为unclassified

“…2012年, Wang等 [13] 在对一系列不同β弛豫行为的非晶合金进行高应变速率加载时, 认识到非晶合金黏弹性、塑性变形行为与β弛豫具有共同的结构起源. 通过研究不同塑性和脆性非晶合金快二次弛豫的动力学特征, Wang等 [14] 证实了非晶合金塑性与其"快β弛豫 (fast β relaxation)"弛豫谱强相关. 更为重要的是, 借助于低温压缩实验, 已经证实了激活这种快二次弛豫将会诱导多重剪切带的形成, 进一步使得非晶合金表现出明显的快β弛豫附近的塑性-脆性转变.…”

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Probing microstructural heterogeneity of La-based amorphous alloy under versatile mechanical stimuli

Zhang,

Hao,

Zhang

et al. 2024

Acta Phys. Sin.

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The intrinsic structural heterogeneities of amorphous alloys are closely connected to the thermodynamics and dynamical behavior, such as relaxation/crystallization, glass transition and plastic deformation. However, the structural information is submerged into the meta-stable disordered long-range structure, which made it very difficult to explore the structural heterogeneities of amorphous alloys. A mechanical excitation factor is not sufficient to effectively describe the heterogeneity of the microstructure in amorphous alloys, particularly the correlation between structure and dynamics. To explore the essence of the structure in amorphous alloys, it is necessary to consider the different mechanical stimuli. La62Cu12Ni12Al14 amorphous alloy was selected as model system, dynamic mechanical processes were probed by dynamic mechanical analysis (DMA). The contributions of a relaxation and b relaxation processes were described in the framework of the quasi-point defects theory. Based on the quasi-point defect theory, the α-relaxation and β relaxation in the La-based amorphous alloy were separated. Tensile strain rate jump measurements were conducted to study the high temperature rheological behavior of amorphous alloy. The contributions of elasticity, anelasticity as well as plastic deformation during the plastic rheology of amorphous alloy are determined within the framework of quasi-point defects theory. The current work aims to reveal the structural heterogeneities of amorphous alloys under the action of dynamics with various temporal scales. The physical background of the activation, propagation and coalescence of defects in amorphous alloys under different mechanical stimuli were reviewed.

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Anelastic relaxation considering physical aging effects in a high-entropy metallic glass

Duan,

Xu,

Zhang

et al. 2024

Sci. China Technol. Sci.

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Structural rejuvenation and relaxation of a metallic glass under the periodically thermal-mechanical loading

Cited by 12 publications

References 64 publications

Effects of cooling rate on <i>β</i> relaxation process and stress relaxation of La-based amorphous alloys

Effects of cooling rate on <i>β</i> relaxation process and stress relaxation of La-based amorphous alloys

Probing microstructural heterogeneity of La-based amorphous alloy under versatile mechanical stimuli

Anelastic relaxation considering physical aging effects in a high-entropy metallic glass

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