Polymeric binder blended from thermoplastic and uncured elastomer binds magnetizable particulate in segmentally magnetizable materials used for encoder targets used in encoders and assemblies where encoders determine rate of motion. The polymeric binder has a dynamic mechanical thermal analyzer tangent delta value (ASTM E 1640-94) not greater than 0.1 at a temperature not less than the liquefaction supra point temperature of the thermoplastic when cured with radiation (preferably electron beam radiation) prior to being blended with either the magnetizable particulate or with other filler materials. The binder effects encoder targets evidencing robustness to thermal or chemical agent stress. Pre-cured blends of magnetizable particulate in the binder evidence good extrusion (pultrusion) performance.