实际服役过程中低压开关的过早失效主要归因于电弧侵蚀，因此阐明材料微观结构、力学性能退化及电弧侵蚀机理对进一步开发环保MAX相增强银基复合电接触材料进而推动低压开关材料更新换代具有重要意义。本工作沿Ag/Ti₂SnC电触头横截面从电弧侵蚀层到近电弧侵蚀层再到基体内部依次进行了微/纳米压痕实验，分析对比了不同区域显微硬度、纳米硬度、弹性模量、蠕变以及塑性/弹性性能沿电弧侵蚀方向的梯度变化行为。在综合分析不同区域微观形貌和元素组成的基础上，揭示了增强相Ti₂SnC和Ag基体的结构和成分演变，解析了Ag/Ti₂SnC复合材料微观结构梯度变化与微/纳米力学性能之间的内在关系。使用COMSOL模拟进一步验证了多场耦合侵蚀下Ag/Ti₂SnC复合材料的物理特征，进而提出电弧侵蚀机理。

Silver (Ag)-matrix-composite electrical contact materials (ECMs) are widely used in railway, manufacturing, electric power distribution, and aerospace systems, owing to their excellent electrical and thermal conductivities and good mechanical and anti-erosion properties. In particular, they play a key role in low-voltage switches, which are vital in the global electrical economy. To date, substituting the toxic Ag/CdO ECMs has become a bottleneck in the development of low-voltage switches. Over the past decades, Ag/SnO₂, Ag/ZnO, Ag/Ni, and Ag/C have been exploited as substitutes for Ag/CdO ECMs, but their intrinsic defects make them unsuitable; therefore, there is still an urgent need to develop eco-friendly substitutes for CdO. Recently, MAX-phase materials, which combine attractively dual metal and ceramic properties, have shown potential in replacing CdO as a reinforcement for Ag-matrix composites. Moreover, arc erosion is a common cause of the premature failure of low-voltage switches in applications. To aid the further development of MAX-reinforced Ag-matrix-composite contacts, there is a need to understand the mechanism of arc erosion and degradation of the microstructural and mechanical properties of the composites. Nano-indentation is the most common and stable method of evaluating the micromechanical properties of materials. In this study, micro-/nano-indentation tests were performed along the cross-section of Ag/Ti₂SnC contacts (from the arc erosion layer to the near arc erosion layer and then to the matrix interior). The gradient variation of the microhardness, nanohardness, modulus, creep behavior, and plastic/elastic depth in different areas was analyzed and contrasted in the direction of the electrical arc erosion. The micromorphology and elemental composition were comprehensively analyzed, and the structural and compositional evolution of the Ti₂SnC reinforcement phase and Ag matrix were investigated. The relationship between the gradient structural change and micro-/nano-mechanical properties of the Ag/Ti₂SnC composites was analyzed. COMSOL simulations were employed to further demonstrate the physical characteristics of multi-field coupled erosion in the Ag/Ti₂SnC composites; based on these analyses, we propose an erosion mechanism for the composites. This study not only provides insights into the intrinsic relationship between the structure and properties of Ag/MAX composites under arc erosion but also paves the way for the future design and development of eco-friendly contact materials for low-voltage switches.