Sonochemistry can also be used to weld metals which are not normally feasible to join, or form novel alloys on a metal surface. This is distantly related to the method of calibrating ultrasonic cleaners using a sheet of aluminium foil and counting the holes. The holes formed are a result of microjet pitting resulting from cavitation near the surface, as mentioned previously. Due to the aluminium foil's thinness and weakness, the cavitation quickly results in fragmentation and destruction of the foil.