Apparatus includes a magnetostrictive actuator of a medical ultrasound transducer assembly. The actuator comprises a magnetostrictive alloy chosen from a list. A medical ultrasound handpiece includes an ultrasound transducer assembly adapted to attachingly receive an end effector. The transducer assembly includes a magnetostrictive actuator having a magnetostrictive alloy, and includes a first coil surrounding the actuator and adapted to excite the actuator to substantially a desired medical resonant frequency and substantially a desired medical amplitude. A medical ultrasound system includes a handpiece housing, a first medical ultrasound transducer assembly, and a first medical end effector attachable to the first transducer assembly. The first transducer assembly includes a magnetostrictive first actuator having a first magnetostrictive alloy. At least a portion of the first transducer assembly is attachingly insertable in the handpiece housing without the use of tools, without damaging the handpiece housing, and without damaging the first transducer assembly.