Abstract: Composite constructions of this invention comprise a first structural phase formed from a hard material selected from the group consisting of cermet materials, polycrystalline diamond, polycrystalline cubic boron nitride, and mixtures thereof, and a second structural phase formed from a material that is relatively softer than that used to form the first structural phase. The material selected to form the second structural phase can be the same or different from that used to form the first structural phase. The second structural phase is positioned into contact with at least a portion of the first structural phase. The composite construction includes repeated structural units that each comprise an ordered microstructure of first and second structural phases.

Abstract: A hardfacing material for shirttail and gage surfaces of a rock bit cone and a gage row of rock bit teeth comprises steel in the range of from 20 to 40 percent by weight, and tungsten carbide particles in the range of from 60 to 80 percent by weight which contains single crystal monotungsten carbide particles having a particle size primarily less than about 200 mesh with a preferred average particle size in the range of from 30 to 70 microns. According to further embodiments, carburized tungsten carbide particles and/or spherical cast carbide particles are mixed with the single crystal monotungsten carbide in the hardfacing. The carburized tungsten carbide particles have a particle size in the range of from about 10 to 50 microns. The spherical cast tungsten carbide particles have a particle size in the range of from about 20 to 150 microns. The particle size distributions of the tungsten carbide particles are bimodal or trimodal for improved weldability and wear resistance in the hardfacing.

Abstract: An improved hardfacing for teeth and other surfaces of milled tooth rock bits comprises a hard phase of carbide particles embedded in a toughened steel matrix containing no more than 10 percent by volume of combined eta phase and oxide particle components. Eta phase and oxide particle formation is minimized during oxyacetylene welding by positioning the weld rod in a preferred region of the torch flame while welding the hardfacing to the rock bit. The matrix is strengthened by uniformly dispersing ultra-fine carbide or boride particles in the steel alloy. The hardfacing is further toughened by selecting tough carbide particles for the hard phase. Accordingly, the hard phase comprises spherical cast carbide and spherical cemented carbide particles having particle sizes in the range of from 75 .mu.m to 590 .mu.m.

Abstract: An improved hardfacing for teeth and other surfaces of milled tooth rock bits includes steel in the range of from 20 to 50 percent by weight, and filler in the range of from 50 to 80 percent by weight. The filler includes spherical cast tungsten carbide particles alone or in a mixture of other tungsten carbide particles such as crushed cast spherical or crushed cemented tungsten carbide, macrocrystalline tungsten carbide, or the like. The single crystal monotungsten tungsten carbide particles have a particle size in the range of from 16 to 40 mesh and/or in the range of from 80 to 200 mesh.

Abstract: An improved hard facing for teeth and other surfaces of milled tooth rock bits comprises steel in the range of from 18 to 32 percent by weight, and filler in the range of from 68 to 82 percent by weight. The filler is cemented tungsten carbide and cast tungsten carbide free, and includes greater than 95 percent by weight single crystal monotungsten carbide particles. The single crystal monotungsten carbide particles have a particle size in the range of from 200 to 500 mesh and, preferably in the range of from 200 to 325.