Metallic glass composites represent a unique alloy design strategy comprising of in situ crystalline dendrites in an amorphous matrix to achieve damage tolerance unseen in conventional structural materials. They are promising for a range of advanced applications including spacecraft gears, high-performance sporting goods and bio-implants, all of which demand high surface degradation resistance. Here, we evaluated the phase-specific electrochemical and friction characteristics of a Zr-based metallic glass composite, Zr_56.2Ti_13.8Nb_5.0Cu_6.9Ni_5.6Be_12.5, which comprised roughly of 40% by volume crystalline dendrites in an amorphous matrix. The amorphous matrix showed higher hardness and friction coefficient compared to the crystalline dendrites. But sliding reciprocating tests for the composite revealed inter-phase delamination rather than preferred wearing of one phase. Pitting during potentiodynamic polarization in NaCl solution was prevalent at the inter-phase boundary, confirming that galvanic coupling was the predominant corrosion mechanism. Scanning vibration electrode technique demonstrated that the amorphous matrix corroded much faster than the crystalline dendrites due to its unfavorable chemistry. Relative work function values measured using scanning kelvin probe showed the amorphous matrix to be more electropositive, which explain its preferred corrosion over the crystalline dendrites as well as its characteristic friction behavior. This study paves the way for careful partitioning of elements between the two phases in a metallic glass composite to tune its surface degradation behavior for a range of advanced applications.

中文翻译：

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金属玻璃复合材料在微观结构长度尺度上的电化学和摩擦特性。


金属玻璃复合材料代表了一种独特的合金设计策略，包括非晶基体中的原位结晶枝晶，以实现传统结构材料中未见的损伤容限。它们有望用于一系列先进应用，包括航天器齿轮、高性能体育用品和生物植入物，所有这些都需要高表面抗降解性。在这里，我们评估了 Zr 基金属玻璃复合材料 Zr _56.2 Ti _13.8 Nb _5.0 Cu _6.9 Ni _5.6 Be _12.5的相特异性电化学和摩擦特性，该复合材料在非晶基体中包含约 40% 体积的结晶枝晶。与结晶枝晶相比，非晶基体表现出更高的硬度和摩擦系数。但复合材料的滑动往复测试揭示了相间分层，而不是一相的优先磨损。氯化钠溶液中动电位极化期间的点蚀在相间边界处普遍存在，证实电耦合是主要的腐蚀机制。扫描振动电极技术表明，由于其不利的化学性质，非晶基体的腐蚀速度比晶态枝晶快得多。使用扫描开尔文探针测量的相对功函数值显示非晶基体更具正电性，这解释了它比晶态枝晶更容易腐蚀以及其特征摩擦行为。这项研究为金属玻璃复合材料中两相之间的元素仔细分配铺平了道路，以调整其表面降解行为，以适应一系列先进应用。