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A matrix drill bit and method of manufacturing a matrix bit body from a composite of matrix materials is disclosed. Two or more different types of matrix materials may be used to form a composite matrix bit body. A first matrix material may be selected to provide optimum fracture resistance (toughne

A matrix drill bit and method of manufacturing a matrix bit body from a composite of matrix materials is disclosed. Two or more different types of matrix materials may be used to form a composite matrix bit body. A first matrix material may be selected to provide optimum fracture resistance (toughness) and optimum erosion, abrasion and wear resistance for portions of a matrix bit body such as cutter sockets, cutting structures, blades, junk slots and other portions of the bit body associated with engaging and removing formation materials. A second matrix material may be selected to provide desired infiltration of hot, liquid binder material with the first matrix material to form a solid, coherent, composite matrix bit body.

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What is claimed is: 1. A drill bit having a matrix bit body comprising: a plurality of cutting elements disposed at selected locations on exterior portions of the matrix bit body; at least a first matrix material and a second matrix material with the first matrix material having increased resistanc

What is claimed is: 1. A drill bit having a matrix bit body comprising: a plurality of cutting elements disposed at selected locations on exterior portions of the matrix bit body; at least a first matrix material and a second matrix material with the first matrix material having increased resistance to impact as compared with the second matrix material; the first matrix material forming exterior portions of the matrix bit body associated with engaging and removing formation materials from a wellbore; the second matrix material forming interior portions of the matrix bit body which are generally not associated with engaging and removing formation materials from a wellbore; the second matrix material operable to improve infiltration of a hot, liquid binder material throughout the first matrix material to minimize incomplete infiltration of the first matrix material by the hot, liquid binder material; and the second matrix material having a substantially reduced amount of alloys and other potential contaminants which may be leached by hot, liquid binder material as compared with alloys and other potential contaminants which may be leached by hot, liquid binder material from the first matrix material. 2. The matrix drill bit of claim 1 further comprising the second matrix material operable to accommodate alloys or other contaminates leached from the first matrix material by hot, liquid binder material without substantially reducing the quality of bonding formed by the hot, liquid binder material contacting and solidifying with the second matrix material. 3. A drill bit having a matrix bit body comprising: a plurality of cutting elements disposed at selected locations on exterior portions of the matrix bit body; at least a first matrix material and a second matrix material with the first matrix material having increased resistance to impact as compared with the second matrix material; the first matrix material forming exterior portions of the matrix bit body associated with engaging and removing formation materials from a wellbore; the second matrix material forming interior portions of the matrix bit body which are generally not associated with engaging and removing formation materials from a wellbore; the second matrix material operable to improve infiltration of a hot, liquid binder material throughout the first matrix material to minimize incomplete infiltration of the first matrix material by the hot, liquid binder material; and a third matrix material covering the second matrix material. 4. The matrix drill bit of claim 3 wherein the third matrix material comprises at least in part a tungsten powder. 5. A drill bit having a composite matrix bit body comprising: a plurality of cutting elements disposed at select locations on exterior portions of the bit body; the composite matrix bit body having at least a first zone and a second zone disposed adjacent to each other; the first zone formed at least in part by hard particles comprising cemented carbides and at least one binder material selected from the group consisting of cobalt, nickel, iron or alloys of these elements; and the second zone formed at least in part from hard particles selected from the group consisting of macrocrystalline tungsten carbides and cast carbides; the second zone formed by the same binder material as the first zone; and the second matrix material comprises less than four percent alloy materials and other contaminates. 6. A drill bit having a composite matrix bit body comprising: a plurality of cutting elements disposed at select locations on exterior portions of the bit body; the composite matrix bit body having at least a first zone and a second zone disposed adjacent to each other; the first zone formed at least in part by hard particles comprising cemented carbides and at least one binder material selected from the group consisting of cobalt, nickel, iron or alloys of these elements; and the second zone formed at least in part from hard particles selected from the group consisting of macrocrystalline tungsten carbides and cast carbides; the second zone formed by the same binder material as the first zone; and the first zone further comprises hard particles having an alloy concentration of less than approximately six percent. 7. A drill bit having a composite matrix bit body comprising: a plurality of cutting elements disposed at select locations on exterior portions of the bit body; the composite matrix bit body having at least a first zone and a second zone disposed adjacent to each other; the first zone formed at least in part by hard particles comprising cemented carbides and at least one binder material selected from the group consisting of cobalt, nickel, iron or alloys of these elements; and the second zone formed at least in part from hard particles selected from the group consisting of macrocrystalline tungsten carbides and cast carbides; the second zone formed by the same binder material as the first zone; and the hard particles having an alloy concentration between approximately three percent and six percent. 8. A drill bit having a composite matrix bit body comprising: a plurality of cutting elements disposed at select locations on exterior portions of the bit body; the composite matrix bit body having at least a first zone and a second zone disposed adjacent to each other; the first zone formed at least in part by hard particles comprising cemented carbides and at least one binder material selected from the group consisting of cobalt, nickel, iron or alloys of these elements; and the second zone formed at least in part from hard particles selected from the group consisting of macrocrystalline tungsten carbides and cast carbides; the second zone formed by the same binder material as the first zone; and the first matrix material having a concentration of cobalt between about six percent and twenty percent. 9. A drill bit having a composite matrix bit body comprising: a plurality of cutting elements disposed at select locations on exterior portions of the bit body; the composite matrix bit body having at least a first zone and a second zone disposed adjacent to each other; the first zone formed at least in part by hard particles comprising cemented carbides and at least one binder material selected from the group consisting of cobalt, nickel, iron or alloys of these elements; and the second zone formed at least in part from hard particles selected from the group consisting of macrocrystalline tungsten carbides and cast carbides; the second zone formed by the same binder material as the first zone; and the second matrix material having increased wettability when exposed to hot, liquid binder material as compared with wettability of the first matrix material.