While laser based additive manufacturing (AM) offers significant advantages for fabricating intricately shaped metallic components, high incidence of undesired microstructural features and defects remain barriers to a wider industrial adoption of this process. A few recent studies have investigated an approach, referred to as ultrasonically assisted (UA)-AM, that is based on superimposing ultrasonic vibration during laser AM for suppressing defects and refining microstructure. However, the fundamental mechanisms of the UA-AM process are not completely understood, and the current models ignore the transient nature and far-from-equilibrium conditions of the process. This project will utilize synchrotron imaging and diffraction with high space and time resolutions to observe the core mechanisms of the UA-AM process. The knowledge derived from this research can benefit AM industries and facilitate effective and innovative incorporation of UA into various manufacturing processes that involve rapid melting and solidification. The project will contribute to multidisciplinary workforce training and promote STEM education with an e-Learning module and hands-on activities for K-12 students. To observe the underlying physics of UA including the melt dynamics and microstructure evolution, this project will develop an innovative UA laser melting system that fits into the advanced synchrotron radiation facilities. UA effects on the AM process will be analyzed through in situ synchrotron