Relating structural heterogeneity to β relaxation processes in metallic glasses

Abstract

The β relaxation is a crucial feature in metallic glasses (MGs). However, its structural origin is not fully elucidated. Using a contact resonance atomic force microscope, we investigated the local structural heterogeneity of MGs and its correlation with β relaxations. It was found that MGs have various degrees of the heterogeneity, resulting in different intensities of β relaxations. Local zones with a prominent heterogeneity lead to a broad energy state distribution and more pronounced β relaxation. Our results provide a direct experimental evidence to clarify the mechanism of the β relaxations, suggesting a guideline for controlling β relaxations of MGs. IMPACT STATEMENT The structural origin of β relaxations is correlated with structural heterogeneity in metallic glasses. The zones with prominent structural heterogeneity cause a broad energy state distribution and pronounced β relaxations.

Structure-dynamics relationships in cryogenically deformed bulk metallic glass

“…For glasses rejuvenated by HPT or other methods (i.e., by affine cryogenic deformation, elastostatic loading, cold rolling, shot peening, uniaxial compression, triaxial compression) a fair amount of enthalpy relaxation is observed 4 , 6 , 9 , 34 , 35 in the temperature range characteristic for the β -transition. In the range of the β -transition recent literature reported that some glasses tend to stiffen in DMA 16 , 36 due to annihilation of free volume. It can hence be assumed, that rejuvenation and the β -transition are related.…”

Relaxation behavior of high-entropy bulk metallic glass: Influences of physical aging and cyclic loading

“…前期研究通 过实验手段、数值模拟和理论分析已证实微观结构非 均匀性是金属玻璃的内在特征, 这为深入研究金属玻 璃的微观变形机制、微观结构非均匀性与其物理、力 学和化学性能之间的关联提供了有力的依据 [4,14,15] . 属玻璃保留了液体绝大部分的结构信息, 所以弛豫行 为是非晶态材料特别是金属玻璃的内在本质特征之 一 [16,18] . 金属玻璃的弛豫行为受其所处能量状态影响.…”

“…一方面, 玻璃转变温度以下的物理时效会增加金属玻 璃微观结构短程有序度甚至长程有序度. 研究表明, 在玻璃转变温度以下物理时效会诱导Zr基和Pd基金属 玻璃局部结构弛豫, 甚至在室温时效作用下La基金属 玻璃也会发生局部结构弛豫 [16,18,20] ; 另一方面, 应变幅 值低于弹性极限的循环加载被视为"力学时效", 金属 玻璃在连续循环加载后向更稳定状态跃迁 [21][22][23] . 基于 前期研究, 力学处理和热学处理对金属玻璃弛豫行 为、力学性能和塑性等的影响引起了研究者广泛的研 究兴趣.…”

Deformation of Al85Y8Ni5Co2 Metallic Glasses under Cyclic Mechanical Load and Uniform Heating

“…The mentioned impact is one of the widespread pre-treatments such as isothermal annealing [18] and chemical processing [19], which are used at the technology of different materials. The results in this field can broad understanding of the physical processes, related to β-relaxation [20] and hardening because of a strong impact of loading and temperature on continual structure. Moreover, isothermal creep is well investigated both theoretically [21] and experimentally [22] right now, but there are few works on modelling of deformation in metallic glasses at non-stationary conditions (for example, at dynamic mechanical analysis-DMA).…”