EARTH-BORING METAL MATRIX ROTARY DRILL BIT

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An earth-boring rotary drill bit includes a bit body, with a first region configured to carry a plurality of cutters for engaging a subterranean earth formation of a first particle-matrix composite material and a second region configured for attachment to a drill string of a second particle-rnatrix composite material having a second materia! composition, and an annular shank extending from the second region. Each of the first particle- matrix composite material and second particle-matrix composite material has a cast microstructure. A method of making an earth-boring rotary drill bit includes providing a plurality of hard particles in a mold to define a particle precursor; infiltrating the particle precursor sequentially with a plurality of molten matrix materials to form a corresponding plurality of layers, each comprising a particle-matrix mixture; and cooling the plurality of particle-matrix mixtures to solidify the matrix materials and form the bit body.