Gravity and magnetic fields are something that we assume because that are always here.
Years ago I worked with someone that built very sensitive accelerometers, you could put it on the floor and zero it and then put it up on a shelf and measure the change in local gravity.
Yes magnetic materials change volume with magnetization, but not mass. Of course they also change magnetization with changes in volume.
One industrial application of magnetostriction was detonation detectors in aircraft engines. A pin magnet (0.125" diam x 1" long) was tightly wound with a coil, this was installed in a blind hole in the cylinder head with one per cylinder. The flight engineer could look at these signals (one at a time on an oscilloscope) and detect detonation, and thereby adjust the fuel or timing as needed.
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P.E. Metallurgy