castings directly from molten materials produces grain size usually in the range of smaller than 50 u03bcm and can be easily retrofitted into existing conventional forming machine application_number US 72961407 A description the present invention is carried out by u201c ultrasonic processing u201d which comprises vibrating molten process material usually a metal at an ultrasonic frequency as it cools to a semi solid state in order to form non dendritic i e globular shaped rounded ideally spherical grains having an average diameter of no more than 1000 u03bcm preferably no more than 100 u03bcm more preferably no more than 50 u03bcm most preferably no more than 1 u03bcm such grain structure is most beneficial for semi solid forming processes ultrasonic processing in accordance with the present invention generally avoids formation of large and or dendritic grains in the process material in accordance with the present invention vibration at an ultrasonic frequency is operably applied at a frequency in the range of 1 khz to 10 6 khz preferably in the range of 15 khz to 25 khz and at a power intensity in the range of 1 w to 10 6 w preferably in the range of 500 to 1000 w the duration of ultrasonic processing is in the range of 1 millisecond to one hour depending on the type and volume of metal being processed once the beneficial results of ultrasonic processing are achieved continued subjection of the process material is not deleterious therefore duration is not considered to be a critical parameter referring to fig1 an example of a basic apparatus.