Switching performance of W-Ag electrical contacts fabricated by mechanicalalloying

Blended elemental W - 35 w/o Ag powders were mechanically alloyed in a heav y duty attritor mill for times up to 15h followed by compaction, sintering, furnace cooling and re-sintering under industrial conditions. Changes in t he morphology and microstructure of the as-milled powders and the compacts were characterized by scanning electron microscopy which revealed regions o f nominal composition and loose W particles in the as-milled state. X-ray d iffraction scans of the milled powders and compacts showed the presence of W and Ag peaks. Higher densities and hardness values were achieved for comp acts mechanically alloyed at longer times. The arc erosion characteristics of the W-35w/oAg compacts confirmed that the erosion rate of contact materi al decreased with increasing milling time. an the basis of a linear regress ion estimate, all the compacts were found to be so for electrical contact a pplications. In particular, compacts mechanically alloyed for 10h were esti mated to endure more than 3 x 10(6) operations.