Abstract: A nitrogen-containing sintered alloy includes at least 75 and not more than 95 percent by weight of a hard phase containing Ti, a group 6A metal and WC in a prescribed composition, and at least 5 and not more than 25 percent by weight of a binder phase containing Ni, Co and unavoidable impurities. The alloy contains at least 5 and not more than 60 percent by weight of a carbide, nitride or carbonitride of Ti, and at least 30 and not more than 70 percent by weight of a carbide of a metal belonging to the group 6A of the periodic table. The atomic ratio of nitrogen/(carbon+nitrogen) in the hard phase is at least 0.2 and less than 0.5. The alloy includes a soft layer containing a binder phase metal and WC at its outermost surface, and includes a layer that hardly contains any of the hard phase containing WC in a region immediately under the soft layer, with a thickness of at least 3 .mu.m and not more than 30 .mu.m.

Abstract: A titanium carbonitride-based alloy which is excellent in chipping resistance and wear resistance is disclosed. A hard phase is a carbide (TiMC), a nitride (TiMN) or a carbonitride (TiMCN) of Ti and at least one metal (M), other than Ti, selected from those belonging to the groups IVa, Va and VIa of the periodic table. A binder phase contains Co and Ni as main components. When the structure of the titanium-based alloy is observed with a scanning electron microscope, particles forming the hard phase in the alloy have black core parts which are located on core portions to appear black and peripheral parts which are located around the black core parts to appear gray. Assuming that A and B represent particles having the black core parts occupying areas of at least 30% of the overall particles A and those having the black core parts occupying areas of not more than 30% of the overall particles B respectively, the area ratio of the particles A to the particles B satisfies a condition of 0.3.ltoreq.A/(A+B).ltoreq.0.

Abstract: A nitrogen-containing sintered hard alloy in which the content of the binder phase is at the highest level in an area to a depth of between 3 .mu.m and 500 .mu.m from its surface and its content in this area is between 1.1 and 4 times the average content of the binder phase in the entire alloy. Below this area, the content of the binder phase decreases gradually so that its content becomes equal to the average content of the binder phase at a depth of 800 .mu.m or less. The content of the binder phase in the surface layer is 90% or less of its maximum value. The depth of 800 .mu.m is a value at which the thermal conductivity is kept sufficiently high and at the same time a tool can keep high resistance to plastic deformation during cutting.

Abstract: A throw-away tipped drill has an insert removably connected to a shank for cutting a workpiece. The insert (31) and the shank (32) have mutually engaging surfaces respectively, and a slit (34, 39) is formed either in the insert (31) or in the shank (32) for mounting the insert to the shank, whereby the insert (31) is fixed to the shank (32) by an elastic force which is caused by an elastic deformation upon mutual movement of opposite surfaces of this slit (34, 39) in engagement of the insert (31) and the shank (32). Therefore, the insert (31) and the shank (32) are coupled by simple press fitting without any requirement for a screw or other connection, whereby the assembly is improved.

Abstract: A cermet alloy and a drill formed of the cermet alloy include hard dispersed phases and binder metal phases. The hard dispersed phases include a metal atom group containing titanium and a nonmetal atom group containing nitrogen. The amount of titanium contained in the metal atom group is at least 0.5 and not more than 0.95 as an atomic ratio. The amount of nitrogen contained in the nonmetal atom group is at least 0.1 and not more than 0.7 as an atomic ratio. The hard dispersed phases further include a fine grained portion having a mean grain size of at least 0.2 .mu.m and not more than 0.6 .mu.m and a coarse grained portion having a mean grain size of at least 1 .mu.m and not more than 3 .mu.m. The volume ratio of the fine grained portion to the course grained portion is at least 0.3 and not more than 3. The proportion of the binder metal phases contained in the cermet is at least 5 percent by weight and not more than 30 percent by weight.

Abstract: A drill bit has a throw-away drill bit tip in the form of an insert (21, 31) secured to a shank (22, 32) to be mounted in a drilling tool. The insert (21, 31) is disengageably mechanically connected to the shank (22, 32) without any screws. The insert (21, 31) is formed of a silicon carbide whisker reinforced alumina sintered body, and the shank (22, 32) is made of steel. Due to this structure, the insert (21, 31) has an excellent wear resistance and an adhesion resistance. The shank (22, 32) has a sufficient toughness against breakage. Such a drill bit does not require any resharpening for continuous use during bit life.

Abstract: A drill bit has a throw-away drill bit tip in the form of an insert (21, 31) secured to a shank (22, 32) to be mounted in a drilling tool. The insert (21, 31) is disengageably mechanically connected with the shank (22, 32) without any screws. At least a cutting edge of the insert (21, 31) is made of a diamond or cubic boron nitride sintered body, and the shank (22, 32) is made of steel. Due to this structure, the insert (21, 31) has an excellent wear resistance and an adhesion resistance. The shank (22, 32) has sufficient toughness against breakage. Such a drill bit does not require any resharpening for continuous use during bit life.

Abstract: A drill is formed by a hard dispersed phase of WC and a B-1 type solid solution, and a bond metal phase of an iron family metal. The composition of the hard dispersed phase is expressed as (W.sub.a M.sub.b) (C.sub.x N.sub.y), where M represents Ti, or two or more metals, including Ti but excluding W, selected from the group IVa, Va and VIa of the periodic table, and a, b, x and y represents molar fractions which are defined by relational expressions of a+b=1, x+y=1, x>0, y.gtoreq.0 and b.gtoreq.0.4. The bond metal phase occupies at least 13 volume percent and not more than 30 volume percent of the cemented carbide.

Abstract: High hardness and high toughness nitrogen-containing sintered hard alloys or cermets useful for cutting tools, in particular, high speed cutting are provided which comprises a hard dispersed phase consisting essentially of a mixed carbonitride of titanium and at least one element selected from the group consisting of Group IVa, Va, and VIa elements of Periodic Table, except titanium, and a binder metal phase consisting essentially of at least one metal selected from the group consisting of nickel and cobalt, and unavoidable impurities, the hard dispersed phase having previously been subjected to a solid solution forming treatment at a temperature of at least the sintering temperature before sintering.