A solid block of copper begins to slide and deform internally long before it reaches its breaking point.
Engineers have always believed that metals like copper only start to permanently deform once they reach a specific yield point of stress. This high-resolution mapping shows that the boundaries between copper grains actually start sliding against each other much earlier. This movement happens at room temperature and under relatively low pressure. It challenges the fundamental rules used to calculate the strength and lifespan of metal components. Understanding this hidden sliding could lead to more durable materials for buildings and machines.
Anomalous, pre-yield grain-boundary sliding in copper revealed with in-situ high-resolution strain mapping
arXiv · 2604.26515
Grain boundary sliding is typically associated with high temperature deformation in engineering alloys. Here, we examine grain boundary sliding at room temperature in oxygen-free high-conductivity copper under quasi-static tensile testing. By using high-resolution digital image correlation (HRDIC) conducted in-situ within a scanning electron microscope to produce time-series strain maps, we unexpectedly observe that grain boundary sliding occurs extensively prior to macroscopic yield, and before