Methods for degassing and for removing impurities from molten metals are disclosed. These methods can include operating an ultrasonic device in a molten metal bath, and adding a purging gas into the molten metal bath in close proximity to the ultrasonic device.

Ultrasonic probes containing a plurality of gas delivery channels are disclosed, as well as ultrasonic probes containing recessed areas near the tip of the probe. Ultrasonic devices containing these probes, and methods for molten metal degassing using these ultrasonic devices, also are disclosed.

A degassing and grain refinement system for a cast aluminum-based component and a method of achieving both hydrogen gas presence reduction and grain size reduction in a cast aluminum-based component. Ultrasonic vibrations are imparted to both the liquid metal travel path from its source to the mold to achieve the reduction in hydrogen gas in the molten metal, as well as to one or more locations within the mold to achieve relatively small and equiaxed grains in the component upon solidification.

An acoustic rotary liquid processor coupled with high-intensity ultrasonic vibration, rotary stirring, and melt surface stabilizing is described. The processor can be used for the preparation of slurry containing a small fraction of non-dendritic solid particles for semi-solid material processing.