Definition
The term 'polycrystalline' describes a solid material composed of many small crystals or grains of varying sizes and orientations. Imagine a mosaic made of tiny, irregular tiles fitted together. 🧩 Unlike single crystals, polycrystalline materials have grain boundaries where the individual crystals meet. These boundaries can affect the material's properties, such as strength and conductivity. It's a common structure found in many metals, ceramics, and rocks.