This book collects peer reviewed and selected papers presented at 4th International Conference on Materials Engineering and Functional Materials, held in Da Nang, Vietnam, during February 21-23, 2025. The conference provides an international forum for researchers and practitioners to report most recent innovations and developments, summarize state-of-the-art, and exchange ideas and advances in all aspects of material engineering and functional materials. The topics discussed in the book include functional materials, metallic alloys, tool materials, superplastic materials, ceramics and glasses, optoelectronic materials, smart materials, engineering polymers, nuclear fuel materials, sensors, and surfaces. This book will prove to be a useful reference for researchers and practitioners working in the field of materials' engineering and functional materials.