Method for consolidating tought coated hard powders

Abstract

Disclosed herein is a method of consolidating by liquid phae sintering a new class of designed-microstructure particulate material with unprecedented combinations of property extremes called Tough-Coated Hard Powders (TCHPs). The method generally comprises providing a plurality of core particles, wherein the core particles comprise a core material of a first compound; providing an intermediate layer on a majority of the core particles, the intermediate layer comprising a second compound, different in composition from the first compound and having a higher relative fracture toughness, the second compound being capable of bonding with the first compound and being capable of bounding with a metal chosen from iron, cobalt, nickel, copper, titanium, aluminium, magnesiu, lithium, beryllium, silver, gold, and platinum and their mixtures, thereby forming coated particles; and applying an outer layer to the coated particles, the outer layer comprising a metal chosen from iron, cobalt, nickel, and their mixtures to form a substantially continuous outer layer on said intermediate layer, thereby forming component particles of the particulate material; shapping a plurality of the component particles into an article; and sintering the articles to substantialy full density without significant external pressure at a temperature sufficient to liquefy and portion of the outer layer, and for a time sufficient to liquefy a portion of the intermediate layer. The disclosed method leads to sintered particulate materials that may be individually coated with nanolayers of a metal compound having a relatively higher fracture toughness, such a WC or TaC. These coated particles may be additinally coated with a second layer comprising a binder metal, such as Co or Ni. This unique material resuls in multiproperty alloys within the TCHP sintered structure, thus allowing for a combination of normally conflicting performance extremes, including, but not limited to toughness, abrasiveness, chemical wear resistance, and light weight, at levels heretofore unseen in the powder metallurgical art.