Magnetorheological devices, including damping devices, rotary
devices, and haptic systems constructed with said devices are disclosed. The devices
contain dry magnetically-responsive particles, or MR fluids containing the magnetically
responsive particles. The magnetically soft particles characterized by a single
process yield population of atomized particles having a cumulative 10%, 50% and
90% by volume, fraction within specified size, i.e., D10 of from 2 up
to and including a D10 of 5 m, a D50 8 m up
to and including a D50 of 15 m, a D90 of 25 m
up to and including a D90 of 40 m, and characterized by a least
squares regression of log normal particles size against cumulative volume % fraction
of greater than or equal to 0.77.
